Update CHANGELOG.md

CHANGELOG.md

@@ -15,6 +15,7 @@ You should also include the user name that made the change.
 ### Improvements
 - Bull Dashboardを組み込み、ジョブキューの確認や操作を行えるように @syuilo
 - Check that installed Node.js version fulfills version requirement @ThatOneCalculator
+- Server: performance improvements @syuilo
 
 ### Bugfixes
 - API: fix endpoint endpoint @Johann150