Set up minimum configuration for FastAPI Italian docs

[csr]

Starting the Italian translation efforts for the FastAPI documentation.

Here's the PR.

[csr]

Waiting for it to be merged, although some coverage checks are failing.

I'm not sure why those checks are failing if I've only added some docs files. The impacted file is fastapi/concurrency.py (missing coverage), however I've made no changes to that affected that file.