Update CHANGELOG.md for 8.13.6

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CHANGELOG.md

 Please view this file on the master branch, on stable branches it's out of date.
 
+## 8.13.6 (2016-11-17)
+
+- Omniauth auto link LDAP user falls back to find by DN when user cannot be found by UID. !7002
+- Fix no "Register" tab if ldap auth is enabled (#24038). !7274 (Luc Didry)
+- Fix cache for commit status in commits list to respect branches. !7372
+- Fix issue causing Labels not to appear in sidebar on MR page. !7416 (Alex Sanford)
+- Limit labels returned for a specific project as an administrator. !7496
+- Clicking "force remove source branch" label now toggles the checkbox again.
+- Allow commit note to be visible if repo is visible.
+- Fix project Visibility Level selector not using default values.
+
 ## 8.13.5 (2016-11-08)
 
 - Restore unauthenticated access to public container registries

changelogs/unreleased/23824-activity-page-does-not-show-commits-comments.yml

----
-title: Allow commit note to be visible if repo is visible
-merge_request: 
-author: 

changelogs/unreleased/24038-fix-no-register-pane-if-ldap.yml

----
-title: Fix no "Register" tab if ldap auth is enabled (#24038)
-merge_request: 7274
-author: Luc Didry

changelogs/unreleased/24397-load-labels-on-mr-tabs.yml

----
-title: Fix issue causing Labels not to appear in sidebar on MR page
-merge_request: 7416
-author: Alex Sanford

changelogs/unreleased/fix-cache-for-commit-status.yml

----
-title: Fix cache for commit status in commits list to respect branches
-merge_request: 7372
-author:

changelogs/unreleased/fix-uncheckable-label-for-force_remove_source_branch.yml

----
-title: Clicking "force remove source branch" label now toggles the checkbox again
-merge_request: 
-author: 

changelogs/unreleased/fix_saml_ldap_link.yml

----
-title: Omniauth auto link LDAP user falls back to find by DN when user cannot be found
-  by UID
-merge_request: 7002
-author: 

changelogs/unreleased/issue_20245.yml

----
-title: Fix project Visibility Level selector not using default values
-merge_request:
-author:

changelogs/unreleased/rs-issue-24527.yml

----
-title: Limit labels returned for a specific project as an administrator
-merge_request: 7496
-author: