ceph upgrade doc: document CSI image changes
ceph upgrade doc: document CSI image changes

The configuration for using Rook with CSI images has changed somewhat
since v1.0, and users of Ceph's CSI drivers will need to consider some
additional update steps.

Signed-off-by: Blaine Gardner <135b86f2968bdbcc730c10d8ababd343bb675986@suse.com>

rook/rook,rook/rook,rook/rook,rook/nfs,rook/nfs,rook/rook,rook/rook,rook/nfs