Update changelog

CHANGELOG

 Please view this file on the master branch, on stable branches it's out of date.
 
 v 8.2.0 (unreleased)
+  - Fix grouping of contributors by email in graph.
   - Improved performance of replacing references in comments
   - Show last project commit to default branch on project home page
   - Highlight comment based on anchor in URL
@@ -1902,4 +1903,4 @@ v 0.8.0
   - stability
   - security fixes
   - increased test coverage
-  - email notification
+  - email notification
\ No newline at end of file