Update the repo url

mediawiki/github-repo

@@ -1 +1 @@
-https://github.com/davidbarratt/mediawiki-docker
+https://github.com/wikimedia/mediawiki-docker

mediawiki/maintainer.md

@@ -1 +1 @@
-[the Docker Community](%%GITHUB-REPO%%) (*not* the MediaWiki Community or Wikimedia Foundation)
+[Wikimedia Foundation & Docker Community](%%GITHUB-REPO%%)