Clytwynec/jenkins how to doc

@jzoldak  @benpatterson @minhtuev 

Please review.  
Solid. I'm guessing folks not on a whitelist will immediately want to be put on one. Should we give info on what will happen if you're not in either group (e.g., when your pull request is reviewed, it'll be run through a build as needed, or something like that...?)