Clear release notes (#83)

Author: llucax

RELEASE_NOTES.md

@@ -1,10 +1,17 @@
 # Frequenz Microgrid API Client Release Notes
 
+## Summary
+
+<!-- Here goes a general summary of what this release is about -->
+
 ## Upgrading
 
-- This release stops using `betterproto` and `grpclib` as backend for gRPC and goes back to using Google's `grpcio` and `protobuf`.
+<!-- Here goes notes on how to upgrade from previous versions, including deprecations and what they should be replaced with -->
+
+## New Features
 
-    If your code was using `betterproto` and `grpclib`, it now needs to be ported to use `grpcio` and `protobuf` too. Remember to also remove any `betterproto` and `grpclib` dependencies from your project.
+<!-- Here goes the main new features and examples or instructions on how to use them -->
 
-- We are now using base-client v0.6.0.
+## Bug Fixes
 
+<!-- Here goes notable bug fixes that are worth a special mention or explanation -->