update CHANGELOG.md

Author: diodonfrost

CHANGELOG.md

@@ -5,6 +5,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+## [2.5.2] - 2020-02-24
+### Changed
+- Waiting for instances in running state before resuming autoscaling group
+
 ## [2.5.1] - 2020-02-24
 ### Added
 - github ISSUE_TEMPLATE