Guide: pointers

This is the next section of the guide, and it's on pointers. It's not done yet, as I need to write the section on ownership and borrowing, but I figured I'd share the rest now, to get feedback on the rest of it while I take some time to get that right.
Cool. I'm going to leave the reference in for now, because it's consistent with the rest, but making a note to think about it later, once the whole thing is done. I've replaced my version with yours, with one small tweak: just saying 'box' rather than having 'boxed pointer' too. I'm trying to be mega-consistent in the new docs, since we've had a zillion names for everything, and want to stick to just one name. Thanks so much!