chore: update toolkit-lib homepage to API Reference website (#922)

Fixes the following—changes it to
https://docs.aws.amazon.com/cdk/api/toolkit-lib/:
<img width="1229" height="582" alt="Screenshot 2025-10-30 at 11 42 55"
src="https://github.com/user-attachments/assets/8b6d26b0-676b-4bf2-8278-42fc9275d5d4"
/>
_The homepage should be the API reference, not the Construct Library
repo._

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

Author: iankhou

.projenrc.ts

@@ -794,6 +794,7 @@ const toolkitLibTsCompilerOptions = {
 const toolkitLib = configureProject(
   new yarn.TypeScriptWorkspace({
     ...genericCdkProps(),
+    homepage: 'https://docs.aws.amazon.com/cdk/api/toolkit-lib',
     parent: repo,
     name: '@aws-cdk/toolkit-lib',
     description: 'AWS CDK Programmatic Toolkit Library',