docs: fix changelog link

Author: dignifiedquire

CHANGELOG.md

@@ -761,7 +761,7 @@ task::blocking(async {
 - Initial beta release
 
 [Unreleased]: https://github.com/async-rs/async-std/compare/v1.6.3...HEAD
-[1.6.2]: https://github.com/async-rs/async-std/compare/v1.6.2...v1.6.3
+[1.6.3]: https://github.com/async-rs/async-std/compare/v1.6.2...v1.6.3
 [1.6.2]: https://github.com/async-rs/async-std/compare/v1.6.1...v1.6.2
 [1.6.1]: https://github.com/async-rs/async-std/compare/v1.6.0...v1.6.1
 [1.6.0]: https://github.com/async-rs/async-std/compare/v1.5.0...v1.6.0