Update changelog links

Author: kannibalox

CHANGELOG.md

@@ -31,6 +31,7 @@
 - Added a changelog
 - Created dockerfile
 
-[Unreleased]: https://github.com/kannibalox/pyrosimple/compare/v0.9.0...HEAD
+[Unreleased]: https://github.com/kannibalox/pyrosimple/compare/v0.9.1...HEAD
+[0.9.1]: https://github.com/kannibalox/pyrosimple/compare/v0.9.0...v0.9.1
 [0.9.0]: https://github.com/kannibalox/pyrosimple/compare/v0.8.0...v0.9.0
 [0.8.0]: https://github.com/kannibalox/pyrosimple/compare/v0.7.2...v0.8.0