Doc: update swift-guide in kolla-ansible
Doc: update swift-guide in kolla-ansible

In kolla-ansible "quick start" document, the python-openstackclient
is recommended. It is better to validate Swift with "openstack"
commands instead of "swift" commands.

Change-Id: I6287b40f702de2f3c270109803fad8d93a903c01
Closes-Bug: #1732857
Signed-off-by: Tone Zhang <ef9f0d5cdaef78eacff40ea4fa876d9b63c7ea2b@arm.com>

dardelean/kolla-ansible,dardelean/kolla-ansible,dardelean/kolla-ansible