changelog: add notes about closing #13674

[skip ci]

CHANGELOG.md

@@ -20,6 +20,7 @@
 # 5.3.2 (unreleased)
 
 * **Postgres**: Fix template variables error [#13692](https://github.com/grafana/grafana/issues/13692), thx [@svenklemm](https://github.com/svenklemm)
+* **Cloudwatch**: Fix service panic because of race conditions [#13674](https://github.com/grafana/grafana/issues/13674), thx [@mtanda](https://github.com/mtanda)
 
 # 5.3.1 (2018-10-16)