Add option to `publish` to print a Version ID to the HTML

[robertberrington]

The HTML view of the documents doesn't provide a visual indication of "version".

Would it be possible to allow an option to be passed to doorstop publish to print that in the documentation?

I'm using a specs/__version__.py and a call to native python to get a string when I automate document generation, *.zip and git tag.

[neerdoc]

It should be a feature to publish an identification, preferably the git commit hash, to all publish variants to allow an external document review.

[lbiaggi]

@neerdoc at work, we are working on something related to this