Prepare for release v1.5.0 (#363)

Author: shsms

RELEASE_NOTES.md

@@ -1,17 +1,5 @@
 # Frequenz channels 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
 
 - Added support for disabling the overflow-warning log messagess in broadcast receivers, through the `warn_on_overflow` parameter on `Broadcast.new_receiver()` calls.
-
-## Bug Fixes
-
-<!-- Here goes notable bug fixes that are worth a special mention or explanation -->