fix release note formatting

Author: Jens Kürten

docs/release_notes.md

@@ -1,9 +1,14 @@
 ### 0.12.0:
 Breaking changes:
+
 - Changed the names of the events and their classes, to be more consistent:
+
   - `DocumentReleaseEvent` -> `DocumentReleasedEvent`
+
   - `PartReleaseEvent` -> `PartReleasedEvent`
+
   - `EngineeringChangeRelease` -> `EngineeringChangeReleasedEvent`
+
   - `EngineeringChangeCheck`> `EngineeringChangeCheckEvent`
 
 - Event data now consistently uses the attributes `parts` and `documents` instead of `linked_parts` or `attached_parts`