This mediawiki package supports multiple instances, sometimes also
called Wiki Farms or Wiki Families, but you can use it for a single
instance just as well.

This works by copying /var/www/wiki as is to the new desired location
of your wiki(s) like

cp -a /var/www/wiki /srv/my.host/wiki

and creating an Apache config entry (if you use Apache for serving
mediawiki) like

DocumentRoot /srv/my.host/wiki
Alias /skins /usr/share/mediawiki/skins

(this example is for short URLs, e.g. ones w/o a "/wiki/" in the URL)