Create whitepaper folder and add a paper

Add document: "Bitcoin Protocol Layers: The Problematic Address Model and the Output Models Solution", per Ron's request.

Original source: https://docs.google.com/document/d/1CkLNkKTkH1BnmfE--9rZv16rkgZo_2nUy_thDvNcMtg/edit?usp=sharing