docs: nautilus uses ansible 2.9
docs: nautilus uses ansible 2.9

This updates the ansible release required to deploy nautilus with the
stable-4.0 branch.

Signed-off-by: Dimitri Savineau <a50a620e679eed14f4e99998b821cea8884cf228@redhat.com>

ceph/ceph-ansible,ceph/ceph-ansible