Non-programmers are more comfortable in the Wiki. And it's probably safer to keep them there anyway, and edits can be allowed there with fewer safeguards.

Then again I'm not sure how many non-technical folks are willing to dig into GH anyway. I've heard Issues & friends called "too confusing" for "non-technical" folks, in favor of Asana and Jira, of all things. Huge WTF from me since I'd say the opposite is strongly true regardless how "technical" one is, but that's the perception I guess.