(#17) Change changelog

Author: Joshua Sprey

CHANGELOG.md

@@ -5,6 +5,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Added
+- EasyRedmine widget: `Burn-down/up`
 
 ## [v0.2.0] - 2020-12-16
 ### Added