Move Volume & Backup Driver sections up a level

I think having these sections one level higher up makes them
easier to find. When searching, readers are more likely to associate
with a driver for their very real-world equipment,
compared to looking below a set of configuration options.

Change-Id: I14951c94b43a548aad1e8a31747e7cdcc7a2f2e7
Merge "Move Volume & Backup Driver sections up a level"