Include a random device.
* Add a random device
* Use the same rootdev path as MALTA, so the same emulator setups
  can be used with minimal fuss.
Add example on how to use gpart before growfs.  While here, reorder examples
so that the simplest one comes first.

MFC after:	1 month
Sponsored by:	The FreeBSD Foundation
Uniformly refer to a file system as "file system".

MFC after:	1 month
Sponsored by:	The FreeBSD Foundation