Added changelog entry.

Author: semohr

docs/changelog.rst

@@ -66,9 +66,20 @@ For plugin developers:
 * The `fetchart` plugins has seen a few changes to function signatures and
   source registration in the process of introducing typings to the code.
   Custom art sources might need to be adapted.
-
+* We split the responsibilities of plugins into two base classes
+    #. :class:`beets.plugins.BeetsPlugin` 
+        is the base class for all plugins, any plugin needs to inherit from this class.
+    #. :class:`beets.metadata_plugin.MetadataSourcePlugin`
+        allows plugins to act like metadata sources. E.g. used by the MusicBrainz plugin. All plugins
+        in the beets repo are opted into this class where applicable. If you are maintaining a plugin
+        that acts like a metadata source, i.e. you expose any of `track_for_id,
+        album_for_id, candidates, item_candidates, album_distance, track_distance` methods,
+        please update your plugin to inherit from the new baseclass, as otherwise it will
+        not be registered as a metadata source and wont be usable going forward.
+        
 Other changes:
 
+* Refactor: Split responsibilities of Plugins into MetaDataPlugins and general Plugins.
 * Documentation structure for auto generated API references changed slightly.
   Autogenerated API references are now located in the `docs/api` subdirectory.
 * :doc:`/plugins/substitute`: Fix rST formatting for example cases so that each