Write section for Bamboo

[JKrag]

This workflow can be implemented on modern versions of Bamboo without too much struggle using their "gatekeeper" model, but there are a few caveats you need to be aware of.

I have set this up for a customer, so I will try to make at least a readme about it, maybe with help from @timea.

[JKrag]

I never got around to this, and my bamboo experience is now a long way off. I don't think I could reconstruct a decent tutorial at this point so I am un-assigning myself, and hoping that the next person to do this will document.