Update CHANGELOG.md

Author: gkjohnson

CHANGELOG.md

@@ -5,6 +5,9 @@ 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).
 
 ## [0.4.23] - Unreleased
+### Added
+- DebugTilesPlugin: Added support for "boundsColorMode".
+
 ### Fixed
 - QuantizedMeshPlugin: Fixed case where child tiles could be added redundantly.
 - QuantizedMeshPlugin: Fixed case where tiles could throw error on disposal due to be incomplete.