docs(s3-deployment): update development section of readme (#30253)

…ent README

### Reason for this change


The links in the development section of the aws-s3-deployment README are pointing to incorrect locations (files have been moved from those locations), fixed the links.

### Description of changes


There are no code changes, only documentation update

### Checklist
- [x] 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)

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

packages/aws-cdk-lib/aws-s3-deployment/README.md

@@ -489,8 +489,9 @@ new cdk.CfnOutput(this, 'ObjectKey', {
 ## Development
 
 The custom resource is implemented in Python 3.9 in order to be able to leverage
-the AWS CLI for "aws s3 sync". The code is under [`lib/lambda`](https://github.com/aws/aws-cdk/tree/main/packages/aws-cdk-lib/aws-s3-deployment/lib/lambda) and
-unit tests are under [`test/lambda`](https://github.com/aws/aws-cdk/tree/main/packages/aws-cdk-lib/aws-s3-deployment/test/lambda).
+the AWS CLI for "aws s3 sync".
+The code is now in the `@aws-cdk/custom-resource-handlers` package under [`lib/aws-s3-deployment/bucket-deployment-handler`](https://github.com/aws/aws-cdk/tree/main/packages/@aws-cdk/custom-resource-handlers/lib/aws-s3-deployment/bucket-deployment-handler/) and
+unit tests are under [`test/aws-s3-deployment/bucket-deployment-handler`](https://github.com/aws/aws-cdk/tree/main/packages/@aws-cdk/custom-resource-handlers/test/aws-s3-deployment/bucket-deployment-handler/).
 
 This package requires Python 3.9 during build time in order to create the custom
 resource Lambda bundle and test it. It also relies on a few bash scripts, so