Update release-notes

To add an entry to release-nots related to preventing stacking
of power requests to avoid delays in processing when the request
frequency exceeds the processing time.

Signed-off-by: Daniel Zullo <[email protected]>

Author: daniel-zullo-frequenz

RELEASE_NOTES.md

@@ -40,3 +40,4 @@
 - Fixed a bug in `ConfigManagingActor` that was not properly comparing the event path to the config file path when the config file is a relative path.
 - Re-expose `ComponentMetricId` to the docs.
 - Fixed typing ambiguities when building composite formulas on streaming data.
+- Prevent stacking of power requests to avoid delays in processing when the request frequency exceeds the processing time.