Merge pull request #9 from contentstack/chore/readme

chore: add deprecation warning to README

Author: aravindbuilt

README.md

@@ -1,3 +1,6 @@
+> [!WARNING]
+  **This repo is deprecated and no longer maintained. Security updates are not supported. We recommend avoiding its use.**
+
 [![Contentstack](https://www.contentstack.com/docs/static/images/contentstack.png)](https://www.contentstack.com/)
 
 # Webhook listener Using Lambda Function