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.
You introduce 'resources' here but don't define them. Maybe something like:

"At its core, ownership is about 'resources', which are anything that must be acquired before using, and released or closed when no longer needed."