Update CHANGELOG-EE.md for 10.8.3-ee

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CHANGELOG-EE.md

 Please view this file on the master branch, on stable branches it's out of date.
 
+## 10.8.3 (2018-05-30)
+
+### Fixed (1 change)
+
+- Geo - Calculate the wiki checksum even when wiki is disabled. !5772
+
+### Performance (1 change)
+
+- Make Geo::PruneEventLogWorker delete rows more gently. !5835
+
+
 ## 10.8.2 (2018-05-28)
 
 ### Security (3 changes)

ee/changelogs/unreleased/6077-geo-repository-verification-gets-stuck-when-all-projects-have-been-verified-at-least-once.yml

----
-title: Geo - Calculate the wiki checksum even when wiki is disabled
-merge_request: 5772
-author:
-type: fixed

ee/changelogs/unreleased/tc-geo-gently-log-prune.yml

----
-title: Make Geo::PruneEventLogWorker delete rows more gently
-merge_request: 5835
-author:
-type: performance