Update changelog

Author: david-sawatzke

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
+- `RGBCCT` type for RGB + warmwhite + coldwhite LEDs such as the WS2805, FW1906 and UCS512H
 
 ## [0.3.1] - 2024-01-22
 ### Added