chore: add deprecation notice (#39)

Co-authored-by: Atif Ali <me@matifali.dev>

Author: sreya

README.md

@@ -1,3 +1,6 @@
+> [!CAUTION]
+> This integration is no longer supported in [Coder](https://github.com/coder/coder) as of `v2.22.0`
+
 # coder-xray
 
 [![release](https://img.shields.io/github/v/tag/coder/coder-xray)](https://github.com/coder/coder-xray/pkgs/container/coder-xray)