[tor-dev] use sphinx on stem

[Damian Johnson]

> Do you need any help on this, or you can
> complete all the work by yourself and I should move to another task
> (maybe events)?

Nope, I should be fine finishing this on my own. Events would be a
great thing to work on next. I haven't written any examples but
hopefully it won't be too hard to figure out - let me know if you have
any questions!

I'd suggest starting with BW events since they'll be the easiest to
test (due to being reliably emitted every second).

Cheers! -Damian