docs: Adding disclaimers reflect the new monorepo setup (#1157)

JIRA: CPOUI5FOUNDATION-975

---------

Co-authored-by: Max Reichmann <[email protected]>

Author: d3xter666

README.md

@@ -1,6 +1,15 @@
 ![UI5 icon](https://raw.githubusercontent.com/UI5/cli/main/docs/images/UI5_logo_wide.png)
 
 # ui5-builder
+
+> ⚠️ **REPOSITORY MOVED**
+> 
+> The `@ui5/builder` package is now maintained in the [UI5 CLI monorepo](https://github.com/UI5/cli). This repository contains the code up to and including CLI version 4, with further development continuing in the monorepo.
+> 
+> - **New location**: https://github.com/UI5/cli/tree/main/packages/builder
+> - **Issues & PRs**: Please submit to the [monorepo](https://github.com/UI5/cli/issues)
+> - **Latest releases**: Available from the monorepo
+
 > Modules for building UI5 projects  
 > Part of the [UI5 CLI](https://github.com/UI5/cli)