I guess I’m not exactly sure what you were looking to do then. Are you looking for a complete replacement of Trello? Or just a method of revisions on final drafts before publishing? Or method to submit changes to already-published docs?
I think it’s already difficult enough for you just getting authors to submit in Markdown, now they’d all have to have learn Git! That’s a tall order!
Since Github doesn’t have free private repositories, authors are likely to use BitBucket or something else to manage their articles, but again I think it’s a lot to ask authors to have to learn git and manage repositories for articles now. I could be very wrong, due to the nature of Sitepoint material, maybe most authors already use Git? But the point is where you host I guess, as long as it’s still free for authors and doesn’t require us to use one service for our private repositories, then transfer to a different service to work on the Sitepoint version etc.
I’m trying to imagine the workflow from article ideas and discussion all the way through to publishing and future revising.
It would nice if all of it could work in a single tool with a single login/interface, ya know? Hoping between forums and Trello and Git and WP is not nice 