AWS Cloud9 Update: Documentation updates for Cloud9

Author: AWS

.changes/next-release/feature-AWSCloud9-fbc5a44.json

@@ -0,0 +1,6 @@
+{
+    "type": "feature",
+    "category": "AWS Cloud9",
+    "contributor": "",
+    "description": "Documentation updates for Cloud9"
+}

services/cloud9/src/main/resources/codegen-resources/service-2.json

@@ -329,7 +329,7 @@
         },
         "imageId":{
           "shape":"ImageId",
-          "documentation":"<p>The identifier for the Amazon Machine Image (AMI) that's used to create the EC2 instance. You can specify the AMI for the instance using an AMI alias or an AWS Systems Manager (SSM) path. The default AMI is used if the parameter isn't explicitly assigned a value in the request. </p> <p> <b>AMI aliases </b> </p> <ul> <li> <p>Amazon Linux 2: <code>amazonlinux-2-x86_64</code> </p> </li> <li> <p>Ubuntu 18.04: <code>ubuntu-18.04-x86_64</code> </p> </li> <li> <p>Amazon Linux (default): <code>amazonlinux-1-x86_64</code> </p> </li> </ul> <p> <b>SSM paths</b> </p> <ul> <li> <p>Amazon Linux 2: <code>resolve:ssm:/aws/service/cloud9/amis/amazonlinux-2-x86_64</code> </p> </li> <li> <p>Ubuntu 18.04: <code>resolve:ssm:/aws/service/cloud9/amis/ubuntu-18.04-x86_64</code> </p> </li> <li> <p>Amazon Linux (default): <code>resolve:ssm:/aws/service/cloud9/amis/amazonlinux-1-x86_64</code> </p> </li> </ul>"
+          "documentation":"<p>The identifier for the Amazon Machine Image (AMI) that's used to create the EC2 instance. To choose an AMI for the instance, you must specify a valid AMI alias or a valid AWS Systems Manager (SSM) path.</p> <p>The default AMI is used if the parameter isn't explicitly assigned a value in the request. </p> <p> <b>AMI aliases </b> </p> <ul> <li> <p> <b>Amazon Linux (default): <code>amazonlinux-1-x86_64</code> </b> </p> </li> <li> <p>Amazon Linux 2: <code>amazonlinux-2-x86_64</code> </p> </li> <li> <p>Ubuntu 18.04: <code>ubuntu-18.04-x86_64</code> </p> </li> </ul> <p> <b>SSM paths</b> </p> <ul> <li> <p> <b>Amazon Linux (default): <code>resolve:ssm:/aws/service/cloud9/amis/amazonlinux-1-x86_64</code> </b> </p> </li> <li> <p>Amazon Linux 2: <code>resolve:ssm:/aws/service/cloud9/amis/amazonlinux-2-x86_64</code> </p> </li> <li> <p>Ubuntu 18.04: <code>resolve:ssm:/aws/service/cloud9/amis/ubuntu-18.04-x86_64</code> </p> </li> </ul>"
         },
         "automaticStopTimeMinutes":{
           "shape":"AutomaticStopTimeMinutes",