Misleading get_result timeout in documentation

[mrtolkien]

The doc defines get_result here: https://dramatiq.io/reference.html?highlight=get_result#dramatiq.Message.get_result

It says the default is timeout=None, but there is an undocumented 10s timeout default.

Either timeout=None should mean no timeout (imo best solution), or the doc should say it defaults to 10s.