docs(logs-destinations): correctly set package description in README (#…

…21570)

The README uses a "for AWS XXX" description as the main header. This updates that header
to match the format used for the Kinesis Destinations and Lambda Destinations libraries.

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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 Unconventional Dependencies:

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

packages/@aws-cdk/aws-logs-destinations/README.md

@@ -1,4 +1,4 @@
-# CDK Construct Libray for AWS XXX
+# AWS CloudWatch Logs Subscription Destination Library
 <!--BEGIN STABILITY BANNER-->
 
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