docs: fix typo on ceph bucket claim description
docs: fix typo on ceph bucket claim description

Signed-off-by: Otto Yiu <902287fd106bdc113344bdf7dbeb396c4c387b6b@live.ca>

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