Added change links

Author: caemor

CHANGELOG.md

@@ -32,5 +32,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 Initial release
 
-[Unreleased]: https://github.com/japaric/linux-embedded-hal/compare/v0.1.1...HEAD
+[Unreleased]: https://github.com/japaric/linux-embedded-hal/compare/v0.2.1...HEAD
+[v0.2.1]: https://github.com/rust-embedded/linux-embedded-hal/compare/v0.2.0...v0.2.1
+[v0.2.0]: https://github.com/rust-embedded/linux-embedded-hal/compare/v0.1.1...v0.2.0
 [v0.1.1]: https://github.com/japaric/linux-embedded-hal/compare/v0.1.0...v0.1.1