missing changelog (closes #889)

Author: Stephan Dilly

Diff for: CHANGELOG.md

@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ![emojified-commit-message](assets/emojified-commit-message.png)
 
 ## Added
+- visualize progress during async syntax highlighting ([#889](https://github.com/extrawurst/gitui/issues/889))
 - added support for markdown emoji's in commits [[@andrewpollack](https://github.com/andrewpollack)] ([#768](https://github.com/extrawurst/gitui/issues/768))
 - added scrollbar to revlog [[@ashvin021](https://github.com/ashvin021)] ([#868](https://github.com/extrawurst/gitui/issues/868))