chore(cli): clarify use case of --no-staging flag (#23827)

We got some customer feedback that this was confusing and easy to interpret in a way that makes it desirable to use `--no-staging` for general usage.

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### All Submissions:

* [x] Have you followed the guidelines in our [Contributing guide?](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md)

### Adding new Construct Runtime Dependencies:

* [ ] This PR adds new construct runtime dependencies following the process described [here](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md/#adding-construct-runtime-dependencies)

### New Features

* [ ] Have you added the new feature to an [integration test](https://github.com/aws/aws-cdk/blob/main/INTEGRATION_TESTS.md)?
	* [ ] Did you use `yarn integ` to deploy the infrastructure and generate the snapshot (i.e. `yarn integ` without `--dry-run`)?

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

Author: mrgrain

packages/aws-cdk/lib/cli.ts

@@ -79,7 +79,7 @@ async function parseCommandLineArguments(args: string[]) {
     .option('path-metadata', { type: 'boolean', desc: 'Include "aws:cdk:path" CloudFormation metadata for each resource (enabled by default)', default: true })
     .option('asset-metadata', { type: 'boolean', desc: 'Include "aws:asset:*" CloudFormation metadata for resources that uses assets (enabled by default)', default: true })
     .option('role-arn', { type: 'string', alias: 'r', desc: 'ARN of Role to use when invoking CloudFormation', default: undefined, requiresArg: true })
-    .option('staging', { type: 'boolean', desc: 'Copy assets to the output directory (use --no-staging to disable, needed for local debugging the source files with SAM CLI)', default: true })
+    .option('staging', { type: 'boolean', desc: 'Copy assets to the output directory (use --no-staging to disable the copy of assets which allows local debugging via the SAM CLI to reference the original source files)', default: true })
     .option('output', { type: 'string', alias: 'o', desc: 'Emits the synthesized cloud assembly into a directory (default: cdk.out)', requiresArg: true })
     .option('notices', { type: 'boolean', desc: 'Show relevant notices' })
     .option('no-color', { type: 'boolean', desc: 'Removes colors and other style from console output', default: false })