Improve guidance for threads in Connexion V3

[chrisinmtown]

Description

Please provide much more information about workers and threads in the new V3. The getting started document advises:

You can still use workers as before, however you should not use threads with ASGI, since it handles concurrency using an async event loop instead.

One of my applications spawns a thread at startup which performs various tasks periodically. Some requests that are sent to Flask by the OpenAPI layer are passed to that thread via a thread-safe queue with appropriate locking etc. No requests result in the code spawning a new thread to handle the request.

Expected behaviour

Documentation explains exactly what thread operations are safe, and which are dangerous.

Actual behaviour

Documentation is vague.