update changelog for 2.0.0

Author: ehough

CHANGELOG.md

@@ -4,7 +4,7 @@ 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).
 
-## [2.0.0] - not yet released
+## [2.0.0] - 2019-01-31
 
 ### Changed
  * Switch to Alpine Linux