chore(appconfig): refactor README and integ tests (#29017)

### Reason for this change

Making changes after API review.

### Description of changes

Refactor README and integ tests.

### Description of how you validated changes



### Checklist
- [ ] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)


----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: chenjane-dev

packages/@aws-cdk/aws-appconfig-alpha/README.md

@@ -18,37 +18,87 @@
 
 This module is part of the [AWS Cloud Development Kit](https://github.com/aws/aws-cdk) project.
 
-Use AWS AppConfig, a capability of AWS Systems Manager, to create, manage, and quickly deploy application configurations. A configuration is a collection of settings that influence the behavior of your application. You can use AWS AppConfig with applications hosted on Amazon Elastic Compute Cloud (Amazon EC2) instances, AWS Lambda, containers, mobile applications, or IoT devices. To view examples of the types of configurations you can manage by using AWS AppConfig, see [Example configurations](https://docs.aws.amazon.com/appconfig/latest/userguide/appconfig-creating-configuration-and-profile.html#appconfig-creating-configuration-and-profile-examples).
+For a high level overview of what AWS AppConfig is and how it works, please take a look here: 
+[What is AWS AppConfig?](https://docs.aws.amazon.com/appconfig/latest/userguide/what-is-appconfig.html)
+
+
+## Basic Hosted Configuration Use Case
+
+> The main way most AWS AppConfig users utilize the service is through hosted configuration, which involves storing 
+> configuration data directly within AWS AppConfig.
+
+An example use case:
+
+```ts
+const app = new appconfig.Application(this, 'MyApp');
+const env = new appconfig.Environment(this, 'MyEnv', {
+  application: app,
+});
+
+new appconfig.HostedConfiguration(this, 'MyHostedConfig', {
+  application: app,
+  deployTo: [env],
+  content: appconfig.ConfigurationContent.fromInlineText('This is my configuration content.'),
+});
+```
+
+This will create the application and environment for your configuration and then deploy your configuration to the 
+specified environment.
+
+For more information about what these resources are: [Creating feature flags and free form configuration data in AWS AppConfig](https://docs.aws.amazon.com/appconfig/latest/userguide/creating-feature-flags-and-configuration-data.html).
+
+For more information about deploying configuration: [Deploying feature flags and configuration data in AWS AppConfig](https://docs.aws.amazon.com/appconfig/latest/userguide/deploying-feature-flags.html)
+
+____
+
+For an in-depth walkthrough of specific resources and how to use them, please take a look at the following sections.
 
 ## Application
 
-In AWS AppConfig, an application is simply an organizational construct like a folder. This organizational construct has a 
-relationship with some unit of executable code. For example, you could create an application called MyMobileApp to organize and 
-manage configuration data for a mobile application installed by your users. Configurations and environments are associated with 
-the application.
+[AWS AppConfig Application Documentation](https://docs.aws.amazon.com/appconfig/latest/userguide/appconfig-creating-namespace.html)
 
-The name and description of an application are optional.
+In AWS AppConfig, an application is simply an organizational 
+construct like a folder. Configurations and environments are 
+associated with the application.
+
+When creating an application through CDK, the name and 
+description of an application are optional.
 
 Create a simple application:
 
 ```ts
 new appconfig.Application(this, 'MyApplication');
 ```
 
-Create an application with a name and description:
+## Environment
+
+[AWS AppConfig Environment Documentation](https://docs.aws.amazon.com/appconfig/latest/userguide/appconfig-creating-environment.html)
+
+Basic environment with monitors:
 
 ```ts
-new appconfig.Application(this, 'MyApplication', {
-  applicationName: 'App1',
-  description: 'This is my application created through CDK.',
+declare const application: appconfig.Application;
+declare const alarm: cloudwatch.Alarm;
+declare const compositeAlarm: cloudwatch.CompositeAlarm;
+
+new appconfig.Environment(this, 'MyEnvironment', {
+  application,
+  monitors: [
+    appconfig.Monitor.fromCloudWatchAlarm(alarm),
+    appconfig.Monitor.fromCloudWatchAlarm(compositeAlarm),
+  ],
 });
 ```
 
+Environment monitors also support L1 `CfnEnvironment.MonitorsProperty` constructs through the `fromCfnMonitorsProperty` method.
+However, this is not the recommended approach for CloudWatch alarms because a role will not be auto-generated if not provided.
+
 ## Deployment Strategy
 
-A deployment strategy defines how a configuration will roll out. The roll out is defined by four parameters: deployment type, 
-step percentage, deployment time, and bake time.
-See: https://docs.aws.amazon.com/appconfig/latest/userguide/appconfig-creating-deployment-strategy.html
+[AWS AppConfig Deployment Strategy Documentation](https://docs.aws.amazon.com/appconfig/latest/userguide/appconfig-creating-deployment-strategy.html)
+
+A deployment strategy defines how a configuration will roll out. The roll out is defined by four parameters: deployment type,
+growth factor, deployment duration, and final bake time.
 
 Deployment strategy with predefined values:
 
@@ -70,13 +120,13 @@ new appconfig.DeploymentStrategy(this, 'MyDeploymentStrategy', {
 });
 ```
 
-Importing a deployment strategy by ID:
+Referencing a deployment strategy by ID:
 
 ```ts
 appconfig.DeploymentStrategy.fromDeploymentStrategyId(this, 'MyImportedDeploymentStrategy', appconfig.DeploymentStrategyId.fromString('abc123'));
 ```
 
-Importing an AWS AppConfig predefined deployment strategy by ID:
+Referencing an AWS AppConfig predefined deployment strategy by ID:
 
 ```ts
 appconfig.DeploymentStrategy.fromDeploymentStrategyId(
@@ -98,6 +148,22 @@ A hosted configuration represents configuration stored in the AWS AppConfig host
 takes in the configuration content and associated AWS AppConfig application. On construction of a hosted configuration, the 
 configuration is deployed.
 
+You can define hosted configuration content using any of the following ConfigurationContent methods:
+
+* `fromFile` - Defines the hosted configuration content from a file (you can specify a relative path). The content type will
+be determined by the file extension unless specified.
+
+```ts
+declare const application: appconfig.Application;
+
+new appconfig.HostedConfiguration(this, 'MyHostedConfiguration', {
+  application,
+  content: appconfig.ConfigurationContent.fromFile('config.json'),
+});
+```
+
+* `fromInlineText` - Defines the hosted configuration from inline text. The content type will be set as `text/plain`.
+
 ```ts
 declare const application: appconfig.Application;
 
@@ -107,18 +173,43 @@ new appconfig.HostedConfiguration(this, 'MyHostedConfiguration', {
 });
 ```
 
-You can define hosted configuration content using any of the following ConfigurationContent methods:
+* `fromInlineJson` - Defines the hosted configuration from inline JSON. The content type will be set as `application/json` unless specified.
 
-* `fromFile` - Defines the hosted configuration content from a file (you can specify a relative path).
-* `fromInlineText` - Defines the hosted configuration from inline text.
-* `fromInlineJson` - Defines the hosted configuration from inline JSON.
-* `fromInlineYaml` - Defines the hosted configuration from inline YAML.
-* `fromInline` - Defines the hosted configuration from user-specified content types.
+```ts
+declare const application: appconfig.Application;
+
+new appconfig.HostedConfiguration(this, 'MyHostedConfiguration', {
+  application,
+  content: appconfig.ConfigurationContent.fromInlineJson('{}'),
+});
+```
+
+* `fromInlineYaml` - Defines the hosted configuration from inline YAML. The content type will be set as `application/x-yaml`.
+
+```ts
+declare const application: appconfig.Application;
+
+new appconfig.HostedConfiguration(this, 'MyHostedConfiguration', {
+  application,
+  content: appconfig.ConfigurationContent.fromInlineYaml('MyConfig: This is my content.'),
+});
+```
+
+* `fromInline` - Defines the hosted configuration from user-specified content types. The content type will be set as `application/octet-stream` unless specified.
+
+```ts
+declare const application: appconfig.Application;
+
+new appconfig.HostedConfiguration(this, 'MyHostedConfiguration', {
+  application,
+  content: appconfig.ConfigurationContent.fromInline('This is my configuration content.'),
+});
+```
 
 AWS AppConfig supports the following types of configuration profiles.
 
-* **Feature flag**: Use a feature flag configuration to turn on new features that require a timely deployment, such as a product launch or announcement.
-* **Freeform**: Use a freeform configuration to carefully introduce changes to your application.
+* **[Feature flag](https://docs.aws.amazon.com/appconfig/latest/userguide/appconfig-creating-configuration-and-profile-feature-flags.html)**: Use a feature flag configuration to turn on new features that require a timely deployment, such as a product launch or announcement.
+* **[Freeform](https://docs.aws.amazon.com/appconfig/latest/userguide/appconfig-free-form-configurations-creating.html)**: Use a freeform configuration to carefully introduce changes to your application.
 
 A hosted configuration with type:
 
@@ -192,24 +283,18 @@ new appconfig.HostedConfiguration(this, 'MyHostedConfiguration', {
 });
 ```
 
-To deploy a configuration to an environment after initialization use the `deploy` method:
-
-```ts
-declare const application: appconfig.Application;
-declare const env: appconfig.Environment;
-
-const config = new appconfig.HostedConfiguration(this, 'MyHostedConfiguration', {
-  application,
-  content: appconfig.ConfigurationContent.fromInlineText('This is my configuration content.'),
-});
+### SourcedConfiguration
 
-config.deploy(env);
-```
+A sourced configuration represents configuration stored in any of the following:
 
-### SourcedConfiguration
+* Amazon S3 bucket
+* AWS Secrets Manager secret
+* Systems Manager 
+* (SSM) Parameter Store parameter
+* SSM document
+* AWS CodePipeline.
 
-A sourced configuration represents configuration stored in an Amazon S3 bucket, AWS Secrets Manager secret, Systems Manager 
-(SSM) Parameter Store parameter, SSM document, or AWS CodePipeline. A sourced configuration takes in the location source 
+A sourced configuration takes in the location source 
 construct and optionally a version number to deploy. On construction of a sourced configuration, the configuration is deployed 
 only if a version number is specified.
 
@@ -356,50 +441,6 @@ new appconfig.SourcedConfiguration(this, 'MySourcedConfiguration', {
 });
 ```
 
-The `deployTo` parameter is used to specify which environments to deploy the configuration to. If this parameter is not 
-specified, there will not be a deployment.
-
-A sourced configuration with `deployTo`:
-
-```ts
-declare const application: appconfig.Application;
-declare const bucket: s3.Bucket;
-declare const env: appconfig.Environment;
-
-new appconfig.SourcedConfiguration(this, 'MySourcedConfiguration', {
-  application,
-  location: appconfig.ConfigurationSource.fromBucket(bucket, 'path/to/file.json'),
-  deployTo: [env],
-});
-```
-
-## Environment
-
-For each AWS AppConfig application, you define one or more environments. An environment is a logical deployment group of AWS 
-AppConfig targets, such as applications in a Beta or Production environment. You can also define environments for application 
-subcomponents such as the Web, Mobile, and Back-end components for your application. You can configure Amazon CloudWatch alarms 
-for each environment. The system monitors alarms during a configuration deployment. If an alarm is triggered, the system rolls 
-back the configuration.
-
-Basic environment with monitors:
-
-```ts
-declare const application: appconfig.Application;
-declare const alarm: cloudwatch.Alarm;
-declare const compositeAlarm: cloudwatch.CompositeAlarm;
-
-new appconfig.Environment(this, 'MyEnvironment', {
-  application,
-  monitors: [
-    appconfig.Monitor.fromCloudWatchAlarm(alarm),
-    appconfig.Monitor.fromCloudWatchAlarm(compositeAlarm),
-  ],
-});
-```
-
-Environment monitors also support L1 CfnEnvironment.MonitorsProperty constructs. However, this is not the recommended approach 
-for CloudWatch alarms because a role will not be auto-generated if not provided.
-
 ## Extension
 
 An extension augments your ability to inject logic or behavior at different points during the AWS AppConfig workflow of 

packages/@aws-cdk/aws-appconfig-alpha/lib/environment.ts

@@ -348,8 +348,11 @@ export abstract class Monitor {
    * @param monitorsProperty The monitors property.
    */
   public static fromCfnMonitorsProperty(monitorsProperty: CfnEnvironment.MonitorsProperty): Monitor {
+    if (monitorsProperty.alarmArn === undefined) {
+      throw new Error('You must specify an alarmArn property to use "fromCfnMonitorsProperty".');
+    }
     return {
-      alarmArn: monitorsProperty.alarmArn!,
+      alarmArn: monitorsProperty.alarmArn,
       alarmRoleArn: monitorsProperty.alarmRoleArn,
       monitorType: MonitorType.CFN_MONITORS_PROPERTY,
     };

packages/@aws-cdk/aws-appconfig-alpha/test/integ.application.js.snapshot/appconfigapplicationDefaultTestDeployAssertD6537C40.assets.json

@@ -4,7 +4,7 @@
    "Type": "AWS::AppConfig::Application",
    "Properties": {
     "Description": "This is my application for testing",
-    "Name": "awsappconfigapplication-MyAppConfig-5BFACBE9"
+    "Name": "MySampleApplication"
    }
   },
   "MyTaskDefTaskRole727F9D3B": {