Fix changelog links

Author: Riimu

CHANGELOG.md

@@ -42,7 +42,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ### Added
 - Initial development release
 
-[Unreleased]: https://github.com/simply-framework/application/compare/v0.2.2...HEAD
+[Unreleased]: https://github.com/simply-framework/application/compare/v0.2.3...HEAD
+[0.2.3]: https://github.com/simply-framework/application/compare/v0.2.2...v0.2.3
 [0.2.2]: https://github.com/simply-framework/application/compare/v0.2.1...v0.2.2
 [0.2.1]: https://github.com/simply-framework/application/compare/v0.2.0...v0.2.1
 [0.2.0]: https://github.com/simply-framework/application/compare/v0.1.0...v0.2.0