docs: Add doc building jobs and doc index page with link
* Rename docs => doc for OpenStack convention compliance
* Add tox.ini job for docs building (no setup.py required)
* Add Makefile with docs entrypoint
* Add a link to the airship-specs subproject.
- Create a site definition to support a full site deployment
workflow using VMs
Enable multi-node gate for Airship using core Airship
Deployment will be driven by Shipyard.
We will re-use and adapt the source codes from the Promenade
g2 Gate .
This PS adds the skeleton for a set of zuul checks and gates for
Airship, using the framework from OpenStack-Helm.
Signed-off-by: Pete Birley <firstname.lastname@example.org>