Update CHANGELOG.md

CHANGELOG.md

@@ -4,7 +4,7 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
-## Unreleased
+## [0.2.1] - 2020-12-15
 ### Added
 - Support for external tile sets.
 - B3DM support for RTC_CENTER.