docs/add warning notice

Author: nexus49

README.md

@@ -1,3 +1,6 @@
+> [!WARNING]
+> This Repository is under development and not ready for productive use. It is in an alpha stage. That means APIs and concepts may change on short notice including breaking changes or complete removal of apis.
+
 # Platform Mesh - rebac-authz-webhook
 ![Build Status](https://github.com/platform-mesh/rebac-authz-webhook/actions/workflows/pipeline.yml/badge.svg)
 
@@ -26,4 +29,4 @@ Please refer to the [CODE_OF_CONDUCT.md](CODE_OF_CONDUCT.md) file in this reposi
 
 ## Licensing
 
-Please see our [LICENSE](LICENSE) for copyright and license information. Detailed information including third-party components and their licensing/copyright information is available via the [REUSE tool](https://api.reuse.software/info/github.com/platform-mesh/rebac-authz-webhook). 
+Please see our [LICENSE](LICENSE) for copyright and license information. Detailed information including third-party components and their licensing/copyright information is available via the [REUSE tool](https://api.reuse.software/info/github.com/platform-mesh/rebac-authz-webhook).