Fixed missing diff links

Author: genius257

CHANGELOG.md

@@ -202,7 +202,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - AutoIt3 syntax highlighting
 - AutoIt2 syntax highlighting
 
-[Unreleased]: https://github.com/genius257/vscode-autoit/compare/1.8.0...HEAD
+[Unreleased]: https://github.com/genius257/vscode-autoit/compare/1.8.1...HEAD
+[1.8.1]: https://github.com/genius257/vscode-autoit/compare/1.8.0...1.8.1
 [1.8.0]: https://github.com/genius257/vscode-autoit/compare/1.7.0...1.8.0
 [1.7.0]: https://github.com/genius257/vscode-autoit/compare/1.6.1...1.7.0
 [1.6.1]: https://github.com/genius257/vscode-autoit/compare/1.6.0...1.6.1