docs(aws-cdk-lib): remove duplication of main docs (aws#35229)

### Issue # (if applicable)

n/a

### Reason for this change

The core docs currently shown in [the API Reference](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib-readme.html) (as of before this PR is merged), is the one at [packages/aws-cdk-lib/README.md](https://github.com/aws/aws-cdk/blob/aaaa9cc330ea1e2854e764e164fe432aeb8606ca/packages/aws-cdk-lib/README.md) and not [packages/aws-cdk-lib/core/README.md](https://github.com/aws/aws-cdk/blob/aaaa9cc330ea1e2854e764e164fe432aeb8606ca/packages/aws-cdk-lib/core/README.md).

Both have a lot of duplication, but there is content that has been added to the core README that is missing from the main doc.

[A long time ago](aws#14280) we enforced both files to have the have the same content, but this got lost in the [big repo remodel of 2023](aws#24376).

### Description of changes

I'm removing the core README.md in favor of the top-level one. 
All missing content has been backported and some additional fixes where made.

### Describe any new or updated permissions being added

n/a

### Description of how you validated changes

I checked and none of the places we publish to uses the current core README.md. This is because the contents get dropped as part of the jsii compilation and doesn't end up in the jsii assembly.

### 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)

----

*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/aws-pipes-alpha/package.json

@@ -114,6 +114,7 @@
   },
   "jsiiRosetta": {
     "exampleDependencies": {
-      "@aws-cdk/aws-pipes-sources-alpha":  "^0.0.0"}
+      "@aws-cdk/aws-pipes-sources-alpha":  "^0.0.0"
+    }
   }
 }