Add note about Window::ClearBackground()

Author: RobLoach

CHANGELOG.md

@@ -4,6 +4,11 @@ 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).
 
+
+## [x.x.x] - xxxx-xx-xx
+### Added
+- `Window::ClearBackground()` ([#127](https://github.com/RobLoach/raylib-cpp/pull/127) by [ufrshubham](https://github.com/ufrshubham))
+
 ## [3.5.0] - 2021-03-24
 ### Added
 - VSCode project template (by [KnockerPulsar](https://github.com/KnockerPulsar))