chore: basic top level readme (#74)

Just listing out the packages of most interest. 

---
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under the terms of the Apache-2.0 license

Author: iliapolo

README.md

@@ -1 +1,22 @@
-# replace this
+# AWS CDK CLI
+
+Command line tools for interacting with AWS CDK applications.
+
+> [!NOTE]
+> Packages in this repository [used to live](https://github.com/aws/aws-cdk/commit/8b87a637d5ce627ebb23637e853558a9ae545b9f) in the
+> main `aws-cdk` repository and were moved here following the decision to split the construct
+> library from the CLI.
+>
+> See [AWS CDK is splitting Construct Library and CLI](https://aws.amazon.com/blogs/opensource/aws-cdk-is-splitting-construct-library-and-cli/)
+
+## Packages
+
+The main packages published from this repository are:
+
+- [`aws-cdk`](https://www.npmjs.com/package/aws-cdk)
+- [`cdk-assets@^3`](https://www.npmjs.com/package/cdk-assets)
+- [`@aws-cdk/cloud-assembly-schema`](https://www.npmjs.com/package/@aws-cdk/cloud-assembly-schema)
+
+## More Information
+
+Refer to each individual package README for more details.