Updated the changelog file

Author: Haojin Yang

CHANGELOG.md

@@ -5,6 +5,12 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
 
+## [0.2.1] - 2024/04/27
+
+### Fixed
+
+- Broken links in README.md and index.rst
+
 ## [0.2.0] - 2024/03/10
 
 ### Added