Added release date [skip ci]

Author: chiao45

CHANGELOG.md

@@ -8,7 +8,7 @@ We follow the [Semantic Versioning](https://semver.org/) policy, which uses `MAJ
 - `MINOR` version when you add functionality in a backwards compatible manner, and
 - `PATCH` version when you make backwards compatible bug fixes.
 
-## [v0.2.0](https://github.com/hifirworks/hifir/releases/tag/v0.2.0) (TBD) ##
+## [v0.2.0](https://github.com/hifirworks/hifir/releases/tag/v0.2.0) (2022-05-22) ##
 
 Changes from [v0.1.0](https://github.com/hifirworks/hifir/releases/tag/v0.1.0) to v0.2.0: