Added CHANGELOG for build notifications

[ci skip]

CHANGELOG

@@ -20,6 +20,7 @@ v 8.7.0 (unreleased)
   - Fall back to `In-Reply-To` and `References` headers when sub-addressing is not available (David Padilla)
   - Remove "Congratulations!" tweet button on newly-created project. (Connor Shea)
   - Improved UX of the navigation sidebar
+  - Build status notifications
 
 v 8.6.4
   - Don't attempt to fetch any tags from a forked repo (Stan Hu)