added changelog

Author: Stephan Dilly

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 
 - Support scrolling in long commit messages [[@cruessler](https://github.com/cruessler)]([#208](https://github.com/extrawurst/gitui/issues/208))
+- Copy lines from diffs to clipboard [[@cruessler](https://github.com/cruessler)]([#229](https://github.com/extrawurst/gitui/issues/229))
 
 ### Fixed