Update CHANGELOG.md

Author: gkjohnson

CHANGELOG.md

@@ -4,6 +4,6 @@ All notable changes to this project will be documented in this file.
 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).
 
-## Unreleased
+## [0.0.1] - 2022-04-08
 
 Initial release with support for path tracing physically based materials with properties including metalness, transmission, roughness, opacity, alpha cutout, and more!