Add Github Actions workflow to build documentation

[alcaeus]

This PR adds a build step to build documentation. This can be used in lieu of building documentation locally as python 2 is no longer available on many platforms. I was not able to make giza make publish exit with a non-zero exit code, even when using a wrong filename to link to a file. For now this means we'll have to verify the docs build manually, but it's better than not being able to run docs at all. The second commit fixes all current warnings.

The built documentation is uploaded as a build artefact to the Docs workflow, accessible through the actions tab.

[alcaeus]

Apparently, this term isn't defined and the current docs don't render this in a special way, so I removed it.

[jmikola]

Thanks. I've seen this error before but never traced it back to this line. I agree this serves no purpose.

It could be something that only builds correctly with the docs team's build tools, since those pull in additional resources used by the server manual (or did if they no longer use Giza).

[alcaeus]

This file (and the next) were lacking a trailing newline.

[jmikola]

Is this worth a PR to mongodb/docs-tools? Worst case it doesn't get merged.

[alcaeus]

Created mongodb/docs-tools#599 to update this.

[jmikola]

@i80and: Any chance you know of a way to get giza to return a non-zero exit code on an erroneous docs build?

Quoting @alcaeus's comment in the OP:

I was not able to make giza make publish exit with a non-zero exit code, even when using a wrong filename to link to a file.