update changelog

Author: Stephan Dilly

CHANGELOG.md

@@ -19,6 +19,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Internal
 - cleanup some stringly typed code [[@wandernauta](https://github.com/wandernauta)] ([#655](https://github.com/extrawurst/gitui/issues/655))
+- introduce EventState enum (removing bool for even propagation) [[@tisorlawan](https://github.com/tisorlawan)] ([#665](https://github.com/extrawurst/gitui/issues/665))
 
 ## [0.14.0] - 2020-04-11