docs: update CHANGELOG.md

Author: markuslf

CHANGELOG.md

@@ -2,7 +2,7 @@
 
 All notable changes to this project will be documented in this file.
 
-The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/)
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
 
 [Unreleased]: https://github.com/Linuxfabrik/monitoring-plugins/compare/v1.2.0.11...HEAD