ready changelog for release (#502)

Author: Elliott Marquez

CHANGELOG.md

@@ -4,7 +4,9 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
-## Unreleased
+<!-- ## Unreleased -->
+
+## [0.9.0] - 2019-09-26
 
 ### Added