Update CHANGELOG for descriptions function addition

Author: benoit74

CHANGELOG.md

@@ -5,7 +5,12 @@ All notable changes to this project are documented in this file.
 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) (as of version 1.5.0).
 
-## [3.1.1]
+## [Unreleased]
+
+### Added
+- Add utility function to compute/check ZIM descriptions #110
+
+## [3.1.1] - 2023-07-18
 
 ### Changed