Fix broken links in changelog

Author: bwestlin

proto-gen/CHANGELOG.md

@@ -72,6 +72,8 @@ and will lead to failed cargo test, and if it is rust code, we definitely don't
 [0.2.4]: https://github.com/EmbarkStudios/proto-gen/compare/0.2.3...0.2.4
 [0.2.3]: https://github.com/EmbarkStudios/proto-gen/compare/0.2.2...0.2.3
 [0.2.2]: https://github.com/EmbarkStudios/proto-gen/compare/0.2.1...0.2.2
-[0.2.1]: https://github.com/EmbarkStudios/proto-gen/compare/0.1.1...0.2.1
+[0.2.1]: https://github.com/EmbarkStudios/proto-gen/compare/0.2.0...0.2.1
+[0.2.0]: https://github.com/EmbarkStudios/proto-gen/compare/0.1.2...0.2.0
+[0.1.2]: https://github.com/EmbarkStudios/proto-gen/compare/0.1.1...0.1.2
 [0.1.1]: https://github.com/EmbarkStudios/proto-gen/compare/0.1.0...0.1.1
 [0.1.0]: https://github.com/EmbarkStudios/proto-gen/releases/tag/0.1.0