updated changelog

Author: ryankurte

CHANGELOG.md

@@ -7,6 +7,14 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 
+### Added
+
+
+### Changed
+
+
+## [v0.2.3] - 2019-05-09
+
 ### Added
 - A new version of the digital `OutputPin`, `StatefulOutputPin`, `ToggleableOutputPin`
   and `InputPin` traits has been added under `digital::v2`. These traits are now