Add a CHANGELOG entry

Signed-off-by: Rémy Coutable <remy@rymai.me>

CHANGELOG

@@ -6,6 +6,7 @@ v 8.11.0 (unreleased)
   - Fix of 'Commits being passed to custom hooks are already reachable when using the UI'
   - Add support for using RequestStore within Sidekiq tasks via SIDEKIQ_REQUEST_STORE env variable
   - Limit git rev-list output count to one in forced push check
+  - Clean up unused routes (Josef Strzibny)
   - Add green outline to New Branch button. !5447 (winniehell)
   - Retrieve rendered HTML from cache in one request
   - Nokogiri's various parsing methods are now instrumented