Topic on Extension talk:WikiMarkdown

1. It is not working in docker, it breaks VisualEditor,User menu, notification button, etc.
2. I tried running `composer install --no-dev` in its folder, got error that it needs php 7.0 which i fixed by running `composer config platform.php 7.0` then 7.2 then 7.2.9. After that it runs install command even on 8.1.29 BUT throws ' Error: Class "ParsedownExtended" not found' even though i am not using extended config