docs: fix typo in section
docs: fix typo in section

The section header was updated to Ceph Pacific since the tag used is
`v16.2.5-20210708`, which means Pacific and not Octopus.

Signed-off-by: Sébastien Han <62d754cc350e84d3b1c32ae79f976f5348e74a40@redhat.com>

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