Try and get them in to a "gotcha" moment: The next time they ask some question already answered on the wiki, point them to it, instead of giving them the answer (unless it's critical that they need the answer RIGHT NOW).
Nudge 'em to explore, and then go to the next step by telling them they can edit all and everything, and add new pages.
Nudge 'em to explore, and then go to the next step by telling them they can edit all and everything, and add new pages.