Wrap instance sizes in code tags, fix spelling

As part of my discussion in #291994 (comment 540492947) go fix the spelling issue I saw.

I pinged @cnorris to let him know we're already back up to 94 spelling issues. This merge request drops it back down to 60, but ugh. We really need to lock this down, but I need buy-in from TW management to turn it on, and I don't believe I have that buy-in at this time.