Update CHANGELOG

[ci skip]

CHANGELOG-EE

 Please view this file on the master branch, on stable branches it's out of date.
 
-v 8.6.0 (unreleased)
+v 8.7.0 (unreleased)
+
+
+v 8.6.1 (unreleased)
+
+
+v 8.6.0
   - Handle duplicate appearances table creation issue with upgrade from CE to EE
   - Add confidential issues
   - Improve weight filter for issues
+  - Update settings and documentation for per-install LDAP sync time
+  - Fire merge request webhooks when a merge request is approved
   - Add full diff highlighting to Email on push
-  - Clear "stuck" mirror updates before periodically updating all mirrors.
+  - Clear "stuck" mirror updates before periodically updating all mirrors
+  - LDAP: Don't render Linked LDAP groups forms when LDAP is disabled
   - [Elastic] Add elastic checker to gitlab:check
   - [Elastic] Added UPDATE_INDEX option to rake task
   - [Elastic] Removing repository and wiki index after removing project
@@ -14,6 +23,7 @@ v 8.6.0 (unreleased)
   - [Elastic] More accurate as_indexed_json (More stable database indexer)
   - [Elastic] Fix: Don't index newly created system messages and awards
   - [Elastic] Fixed exception on branch removing
+  - [Elastic] Fix bin/elastic_repo_indexer to follow config
   - GitLab Geo: OAuth authentication
   - GitLab Geo: Wiki synchronization
   - GitLab Geo: ReadOnly Middleware improvements