CHANGELOG: add 1.2.0 section

Author: zombiezen

CHANGELOG.md

@@ -4,9 +4,13 @@ The format is based on [Keep a Changelog][], and this project adheres to
 [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 [Keep a Changelog]: https://keepachangelog.com/en/1.0.0/
-[Unreleased]: https://github.com/gg-scm/gg/compare/v1.1.0...HEAD
+[Unreleased]: https://github.com/gg-scm/gg/compare/v1.2.0...HEAD
 
-## [Unreleased][]
+## [1.2.0][] - 2022-02-24
+
+Version 1.2 includes features to handle repositories with lots of branches.
+
+[1.2.0]: https://github.com/gg-scm/gg/releases/tag/v1.2.0
 
 ### Added