Adding deprecation announcement to release_notes.md (#9038)

Author: VpOfEngineering

release_notes.md

@@ -2,6 +2,7 @@
 <!-- Please add your release notes in the following format:
 - My change description (#PR)
 -->
+- *Please note we have reached end-of-life (EOL) support for v3.x.* For more information on supported runtime versions, please see [here.](https://learn.microsoft.com/en-us/azure/azure-functions/functions-versions?tabs=v4&pivots=programming-language-csharp)
 - Making feature flag for worker indexing opt-out instead of opt-in
 **Release sprint:** Sprint 133
 [ [bugs](https://github.com/Azure/azure-functions-host/issues?q=is%3Aissue+milestone%3A%22Functions+Sprint+133%22+label%3Abug+is%3Aclosed) | [features](https://github.com/Azure/azure-functions-host/issues?q=is%3Aissue+milestone%3A%22Functions+Sprint+133%22+label%3Afeature+is%3Aclosed) ]