From asvetlov:

Using motor I constantly get a problem: it's not obvious what methods
are coroutines (should be used with `await`/`yield from` statements)
and what are regular methods.

For aiohttp we've solved it by adding `..coroutinemethod:: name()`
markup (borrowed from asyncio).

The code for sphinx plugin is here:
https://github.com/KeepSafe/aiohttp/blob/master/docs/aiohttp_doctools.py

This line connects the plugin:
https://github.com/KeepSafe/aiohttp/blob/master/docs/conf.py#L57

Generated doc looks like
http://aiohttp.readthedocs.org/en/stable/web_reference.html#aiohttp.web.Request.json

Motor has more complicated plugin for collecting documentation but
maybe you would add some markup for coroutines?