Cut 0.4.0 release (#21)

CHANGELOG.md

@@ -5,6 +5,8 @@ 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]
+
+## [v0.4.0] - 2020-03-10
 ### Added
 - Documentation as code; configuration reference.
 - New decision type `median`, returns the median average of the predictions.
@@ -35,7 +37,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 - Added the ability to use Linear Regression models to predict future scaling.
 
-[Unreleased]: https://github.com/jthomperoo/predictive-horizontal-pod-autoscaler/compare/v0.3.0...HEAD
+[Unreleased]: https://github.com/jthomperoo/predictive-horizontal-pod-autoscaler/compare/v0.4.0...HEAD
+[v0.4.0]: https://github.com/jthomperoo/predictive-horizontal-pod-autoscaler/compare/v0.3.0...v0.4.0
 [v0.3.0]: https://github.com/jthomperoo/predictive-horizontal-pod-autoscaler/compare/v0.2.0...v0.3.0
 [v0.2.0]: https://github.com/jthomperoo/predictive-horizontal-pod-autoscaler/compare/v0.1.0...v0.2.0
 [v0.1.0]: https://github.com/jthomperoo/predictive-horizontal-pod-autoscaler/releases/tag/v0.1.0