Update CHANGELOG.md

Author: darrenburns

CHANGELOG.md

@@ -5,6 +5,13 @@ All notable changes to this project will be documented in this file.
 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
+
+- Add support for `FORCE_COLOR` env var https://github.com/Textualize/rich/pull/2449
+
 ## [12.5.2] - 2022-07-18
 
 ### Added