Update CHANGELOG.md

Author: akondas

CHANGELOG.md

@@ -14,6 +14,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## Unreleased
 
+## [0.2.1] 2020-01-29
+### Added
+ * Support for phpstan extension installer #12
+
 ## [0.2.0] 2019-05-15
 ### Fixed
  * support for negation in ObjectState Matcher (not)