Update changelog for 0.22.1 release

Author: turtle0x1

CHANGELOG.md

@@ -4,7 +4,7 @@ All Notable changes to `php-lxd` will be documented in this file.
 
 Updates should follow the [Keep a CHANGELOG](http://keepachangelog.com/) principles.
 
-# Unreleased
+# [0.22.1]
 
 ## Changed
     Don't set "config" and/or "device" properties when replacing profile