Add BCH protocol reference

[melroy89]

Add also a copy of the BCH protocol. Not only as a reference but to further decentralized the protocol definition.

[zquestz]

Agreed, where do we want to put it?

[melroy89]

Can be anywhere like: https://spec.bitcoincash.org

I don't know what source is the best for generate a webpage around the spec. I saw some markdown files here: https://github.com/SoftwareVerde/bitcoin-cash-specification

[zquestz]

Hmm, would be nice to figure that out. Will spend a bit of time looking.