Wikidata deployment/guide

Configuration changes
Wikidata configuration is in https://git.wikimedia.org/summary/operations/mediawiki-config.git


 * wmf-config/Wikibase.php
 * wmf-config/InitialiseSettings.php
 * wmf-config/CommonSettings.php

Checklist

 * make sure all relevant repositories have been branched
 * make sure the branch to be deployed has been tested with the correct branch of core
 * update the relevant submodule pointers on the wmf deployment branch
 * find all mentioned of "DEPLOY" in commit messages of any changes that are new on the branch being deployed, and build a pre/post-deployment checklists from these.