RFC: Handbook Storage chapter RAID section removal

[Warren Block]

The Handbook Storage chapter has a section called RAID that describes 
the use of ccd(4) and ataraid(4).

ccd(4) is obsolete, having been replaced several times by newer drivers. 
I think ataraid(4) has been supplanted by graid(8).

So I propose to remove that RAID section entirely.  Yes, people may 
still be using these devices.  But we should not be recommending them to 
new users.

If you have a reason that should not be done, speak now.