A choicescript tutorial in twine? How about a twine tutorial in choicescript?
This interactive tutorial is pretty straightforward, being just a website/webpage-like guide to choicescript functionality, commands, useful links and so on. I liked the explanation about branching and indents, as that was something my really young self struggled with when learning choicescript for the first time.
Still, I don't think it offers anything you couldn't learn from the website and wiki, and the searchable nature of the wiki probably makes it a better resource once you have passed the initial stages of learning choicescript. Don't get me wrong, this is a well-written and useful resource, just not a strictly necessary one. It is worth taking a look, but you'll also be fine with just the website and wiki, as well as the CoG forums.