Update CHANGELOG.md

Author: kemccusker

CHANGELOG.md

@@ -116,7 +116,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Initial release.
 
-[unreleased]: https://github.com/climateimpactlab/dscim/compare/v0.5.0...HEAD
+[unreleased]: https://github.com/climateimpactlab/dscim/compare/v0.6.0...HEAD
+[0.6.0]: https://github.com/climateimpactlab/dscim/compare/v0.5.0...v0.6.0
 [0.5.0]: https://github.com/climateimpactlab/dscim/compare/v0.4.0...v0.5.0
 [0.4.0]: https://github.com/climateimpactlab/dscim/compare/v0.3.0...v0.4.0
 [0.3.0]: https://github.com/climateimpactlab/dscim/compare/v0.2.1...v0.3.0