Updates changelog

CHANGELOG

@@ -3,10 +3,10 @@ Please view this file on the master branch, on stable branches it's out of date.
 v 8.13.0 (unreleased)
   - Speed-up group milestones show page
   - Fix robots.txt disallowing access to groups starting with "s" (Matt Harrison)
+  - Revoke button in Applications Settings underlines on hover.
 
 v 8.12.2 (unreleased)
   - Fix Import/Export not recognising correctly the imported services.
-  - Revoke button in Applications Settings underlines on hover.
 
 v 8.12.1
   - Fix a memory leak in HTML::Pipeline::SanitizationFilter::WHITELIST