Prepare the CHANGELOG for a 2.0.0 release

Author: mpdude

CHANGELOG.md

@@ -5,7 +5,9 @@ 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 2.0]
+## [Unreleased 2.1]
+
+## Version 2.0.0
 
 ### Removed