Initial commit for always cohort inline discussions plus spelling fix

Suggest avoiding the "shows how" structure (since this *is* how), maybe something more along the lines of "To make all content-specific discussion topics in a course unified, follow these steps."
I'm confused by the inclusion "by default" in this sentence. I think that, maybe, you could introduce the concept of making exceptions earlier, by outlining that these types of topics 1) are divided by default, 2) can all be made unified instead, and 3) if you do make them all unified, you can specify individual discussion topics to be divided again.