Update release_notes.md for SDK

sdk/release_notes.md

@@ -1,4 +1,12 @@
-## Release notes
+## What's Changed
+
 <!-- Please add your release notes in the following format:
 - My change description (#PR/#issue)
 -->
+
+### Microsoft.Azure.Functions.Worker.Sdk <version> (meta package)
+- <entry>
+### Microsoft.Azure.Functions.Worker.Sdk.Analyzers <version> (delete if not updated)
+- <entry>
+### Microsoft.Azure.Functions.Worker.Sdk.Generators <version> (delete if not updated)
+- <entry>