Revamp Onboarding about embedded HOT 2 OPEN

Spent an hour on this, got a decent ways. The work (in terms of code) for this is in david/onboarding, that won't be the permanent place for it, just wanted to save it somewhere other than my computer.

The onboarding document itself is in much rougher shape than the code, but I'll update it in the wiki anyways, as it's probably more informative in it's current state than the existing onboarding. Wiki Onboarding

I want to add another task in onboarding, to listen for incoming Heartbeat messages and then blink according to the number of nodes it sees. That way there's a simpler thing that people can do and they can see the effects of what they wrote by just plugging the board into the rover. I'll probably slightly restructure this so that this task comes before the ADC task, although I believe the ADC is the meat of the whole onboarding thing, as it takes people into proper embedded concepts and is a more practical example of using ChibiOS.

from embedded.

Onboarding is better than it was before, but some more improvements would be nice, so this issue is staying open

from embedded.