Update CHANGELOG.md

Co-authored-by: Jonas Schievink <[email protected]>

Author: adamgreig

CHANGELOG.md

@@ -76,7 +76,7 @@ YANKED due to a soundness issue: see v0.2.1 for details
 - Initial release
 
 [Unreleased]: https://github.com/japaric/bare-metal/compare/v1.0.0...HEAD
-[Unreleased]: https://github.com/japaric/bare-metal/compare/v0.2.5...v1.0.0
+[v1.0.0]: https://github.com/japaric/bare-metal/compare/v0.2.5...v1.0.0
 [v0.2.5]: https://github.com/japaric/bare-metal/compare/v0.2.4...v0.2.5
 [v0.2.4]: https://github.com/japaric/bare-metal/compare/v0.2.3...v0.2.4
 [v0.2.3]: https://github.com/japaric/bare-metal/compare/v0.2.2...v0.2.3