Add CHANGELOG entry for redesigned confirmation emails

[ci skip]

CHANGELOG

@@ -3,6 +3,7 @@ Please view this file on the master branch, on stable branches it's out of date.
 v 8.9.0 (unreleased)
   - Allow forking projects with restricted visibility level
   - Redesign navigation for project pages
+  - Redesign account and email confirmation emails
   - Use gitlab-shell v3.0.0
   - Add rake task 'gitlab:db:configure' for conditionally seeding or migrating the database
   - Changed the Slack build message to use the singular duration if necessary (Aran Koning)