docs: add a CHANGELOG entry for 22f4ee7

Author: williamdes

CHANGELOG.md

@@ -6,7 +6,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased] - yyyy-mm-dd
 
-## [5.2.0] - 2020-xx-xx
+## [5.2.0] - 2020-xx-xx (Unreleased)
+- Support custom composer vendor autoload files using the ENV "DOCTUM_COMPOSER_AUTOLOAD_FILE"
 - Add function reflection & doc section in Namespace (#12)
 
 ## [5.1.0] - 2020-08-29