Ownership guide

This is a work in progress, but this should get *extensive* review, so I'm putting it up early and often.

This is the start of a draft of the new 'ownership guide,' which explains ownership, borrowing, etc. I'm feeling better about this framing than last time's, but we'll see.
I definitely agree with "owning" and "handle" as good words, I just don't recall ever seeing them together as a technical term (maybe I did think of it, but I've forgot if so :P ); something like "owner" is more often used.