Bump version to 0.2.0.

CHANGELOG.md

@@ -9,7 +9,7 @@ The format is based on [Keep a Changelog], and this project adheres to
 [Keep a Changelog]: https://keepachangelog.com/en/1.0.0/
 [Semantic Versioning]: https://semver.org/spec/v2.0.0.html
 
-## [Unreleased]
+## [0.2.0] - 2019-01-29
 
 ### Added
 
@@ -27,6 +27,7 @@ The format is based on [Keep a Changelog], and this project adheres to
 <!-- references -->
 [Unreleased]: https://github.com/dogmatiq/iago
 [0.1.0]: https://github.com/dogmatiq/iago/releases/tag/v0.1.0
+[0.2.0]: https://github.com/dogmatiq/iago/releases/tag/v0.2.0
 
 <!-- version template
 ## [0.0.1] - YYYY-MM-DD