doc.mediawiki.org: Redirect to canonical wikimedia.org and fix invalid SSL

I don't know since when but apparently doc.mediawiki.org has been
registered in addition to doc.wikimedia.org and pointed to the same
server, but Apache was never properly configured for it so we were
serving duplicate content on these 4 different urls, of which one
was causing an invalid certificate error.

 (http/https)://doc.(mediawiki,wikimedia).org
 -> https://doc.wikimedia.org

Bug: 46298
Change-Id: Ideca6e75eb99fde407509acda4057c940bddfb07
Merge "doc.mediawiki.org: Redirect to canonical wikimedia.org and fix invalid SSL" into production