Prepare release notes for release v0.9.0

Signed-off-by: camille-bouvy-frequenz <[email protected]>

Author: camille-bouvy-frequenz

RELEASE_NOTES.md

@@ -1,17 +1,6 @@
 # Frequenz Client Base Library Release Notes
 
-## Summary
-
-<!-- Here goes a general summary of what this release is about -->
-
-## Upgrading
-
-<!-- Here goes notes on how to upgrade from previous versions, including deprecations and what they should be replaced with -->
-
 ## New Features
 
 * Add the `warn_on_overflow` option to the streaming receivers to allow ignoring overflow warnings
 
-## Bug Fixes
-
-<!-- Here goes notable bug fixes that are worth a special mention or explanation -->