Include instructions to refactor to use `?` in the speaker notes

[djmitche]

Sure. In all the cases before here, I think there's been a note to the instructor to this effect when they're supposed to do something.

(I'm just doing the course myself, so there is no instructor!)

Originally posted by @njr0 in #1280 (comment)

[djmitche]

I'll do this in v2.