update CHANGELOG.md

Author: davidjgoss

CHANGELOG.md

@@ -6,6 +6,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
+### Added
+- Add CSS custom properties for overriding fonts ([#372](https://github.com/cucumber/react-components/pull/372))
+
 ### Fixed
 - Avoid NaN percentage passed when nothing ran ([#363](https://github.com/cucumber/react-components/pull/363))
 - Don't render hook steps with no content ([#361](https://github.com/cucumber/react-components/pull/361))