Add tag {'qlwiki'} into article text. Via url parameter you can connect to a wiki; e. g.: {'qlwiki url=http://de.wikipedia.org/wiki/Joomla'}.
If you use a local, private wiki; enter the url in {'qlwiki'} tag or simply use the default settings of plugin in backend. (Of course without '; if I used ' here, iut wouldn't display the tags but the wiki entry;-)