Added changelog for v0.4.0

Author: Phil Sturgeon

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/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
-## [Unreleased]
+## [0.4.0] - 2019-10-04
+### Added
+- Take the first JSON Schema `example` and put in OpenAPI Schema Object `example`
 
 ## [0.3.0] - 2018-12-18
 ### Added