Update CHANGELOG-EE.md for 10.8.4-ee

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CHANGELOG-EE.md

 Please view this file on the master branch, on stable branches it's out of date.
 
+## 10.8.4 (2018-06-06)
+
+### Fixed (4 changes)
+
+- Render a 403 when showing an access denied message. !5964
+- Validate classification label on create & update. !5976
+- Fix breadcrumbs being covered by System Header message.
+- Treat external authorization service response status 403 as failure.
+
+
 ## 10.8.3 (2018-05-30)
 
 - No changes.

ee/changelogs/unreleased/6313-breadcrumbs-with-system-header.yml

----
-title: Fix breadcrumbs being covered by System Header message
-merge_request:
-author:
-type: fixed

ee/changelogs/unreleased/bvl-403-for-external-auth-service.yml

----
-title: Render a 403 when showing an access denied message
-merge_request: 5964
-author:
-type: fixed

ee/changelogs/unreleased/bvl-validate-label-for-project-before-save.yml

----
-title: Validate classification label on create & update
-merge_request: 5976
-author:
-type: fixed

ee/changelogs/unreleased/dm-external-authorization-403.yml

----
-title: Treat external authorization service response status 403 as failure
-merge_request:
-author:
-type: fixed