RFC: Handbook Storage chapter floppy backup section removal

[Warren Block]

Continuing with the project to remove stuff from the Storage chapter 
that is long overdue...

The Backups to Floppies section has been warning that floppies are not 
suitable backup media for a decade now.  New machines have not included 
floppy drives for a long time.  It's time for this section to be 
retired.

I plan to remove this at the same time as the RAID section (ccd(4) and 
ataraid(4)).