Initial experience docs

A start for describing what I have figured out trying to get this to work. I really don't know if it belongs here. So pull if you think it's a good idea. 

From my point of view I just wanted an easy start and explanation. Jumping around all the repos and the mailinglists was quite confusing at first. This is also for some internal documentation, but I tried to make it as general as possible.

I am still a bit confused as to what's happening, but I hope this can be valuable to someone. :) I have probably gotten something wrong too, so please let me know.