Update release notes after release v0.1.0

Signed-off-by: Flora <[email protected]>

Author: flora-hofmann-frequenz

RELEASE_NOTES.md

@@ -10,7 +10,7 @@
 
 ## New Features
 
-* Add cumulative_energy calculation to read out energy consumption and production over a specified time range.
+<!-- Here goes the main new features and examples or instructions on how to use them -->
 
 ## Bug Fixes