https://lists.wikimedia.org/hyperkitty/list/mediawiki-api@lists.wikimedia.org/thread/YAXMI5N7QML77L56CJQD2CWJQTA4ZWPW/
How to get the array $wgFileExtensions in Localsetting.php - Mediawiki-api - lists.wikimedia.org
how to get
https://www.mediawiki.org/wiki/Manual:$wgFileExtensions/de
Handbuch:$wgFileExtensions - MediaWiki
handbuchmediawiki