Update CHANGELOG

CHANGELOG

@@ -1,5 +1,8 @@
 master
 
+* 'pub' now supports Announce activities' default behavior. Upon receiving an
+      Announce activity via S2S, it is added to the 'shares' property of
+      object(s) owned in the application.
 * Add the missing 'shares' property to 'vocab.Object' and its child types as
       well as 'streams.Object' and its child types. It is an ActivityPub
       specific property not a part of the ActivityStreams specification.