Change some .Ar macros to .Pa.
Change some .Ar macros to .Pa.

Describe /dev/vinum/control*

Describe drive "referenced" state.

Remove warning about kldunload; it seems to work now.

Still more descriptions of how to debug things.

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase