docs: add changelog entry

CHANGELOG.md

@@ -5,6 +5,16 @@ 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/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.2.6] - ?
+
+### Added
+
+- New subcommand `metapac clean-cache`! (#61)
+
+  Allows you to clear the caches for all or selective backends.
+  `metapac clean-cache arch apt` to clean just the `arch` and `apt`
+  backends and just `metapac clear-cache` to clear all backends.
+
 ## [0.2.5] - 2024-11-24
 
 ### Added