update changelog.md

Author: mikeebowen

CHANGELOG.md

@@ -5,6 +5,9 @@ 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).
 
+## [1.5.1] - 2022-10-24
+- Updated OOXML Validator to version 2.1.1
+
 ## [1.5.0] - 2022-09-29
 
 ### Added