Update release notes

Signed-off-by: Elzbieta Kotulska <[email protected]>

Author: ela-kotulska-frequenz

RELEASE_NOTES.md

@@ -6,7 +6,8 @@
 
 ## Upgrading
 
-<!-- Here goes notes on how to upgrade from previous versions, including deprecations and what they should be replaced with -->
+- The `ConfigManagingActor` now only reacts to `CREATE` and `MODIFY` events. `DELETE` is not supported anymore and are ignored.
+- Remove the `event_types` argument from the `ConfigManagingActor` constructor.
 
 ## New Features
 
@@ -15,3 +16,8 @@
 ## Bug Fixes
 
 - Fix a bug in the resampler that could end up with an *IndexError: list index out of range* exception when a new resampler was added while awaiting the existing resampler to finish resampling.
+
+- Fix bugs with `ConfigManagingActor`:
+  - Raising unhandled exceptions when any file in config directory was deleted.
+  - Raising unhandled exception if not all config files exist.
+  - Eliminate recursive actor crashes when all config files were missing.