Update CHANGELOG-EE.md for 8.16.8-ee

[ci skip]

CHANGELOG-EE.md

@@ -34,6 +34,10 @@ Please view this file on the master branch, on stable branches it's out of date.
 - Reduce queries needed to check if node is a primary or secondary Geo node.
 - Allow squashing merge requests into a single commit.
 
+## 8.16.8 (2017-03-19)
+
+- Elastic security fix: Respect feature visibility level.
+
 ## 8.16.7 (2017-02-27)
 
 - Fixed merge request state not updating when approvals feature is active.