[CI:DOCS]addition of specgen package

warning: the naming of this might change as well as the location.

this is a build on a PR from mheon from last year that proposes a shift from our current approach of creating containers based on the arbitrarily made createconfig.  the new approach would be to have a specification that is detached from the podman cli.  the spec could then be generated and used to make a container.  this theoretically is the beginning of a long-needed refactor involving how we get from the cli -> libpod | apiv2 -> libpod with code re-use and less duplication.

the intent is to build the apiv2 container creation based on this approach only.  wiring to the podman cli will happen after the fact.

Signed-off-by: Brent Baude <bbaude@redhat.com>