Mediawiki Config Page
http://WEBSERVER_IP_ADDRESS/config/index.php didnt work for me, instead it was localhost/mediawiki/index.php
Version and curl rights
Instead of saving to /usr/share/webapps/ you can also download the latest version to your Downloadsfolder and move the result to /usr/share/webapps/ . This circumvents any rights issues for /usr/share/webapps/
As of this entry alpine doesnt find php7-json automatically when looking for php-json.