Write up Taiga requirements for commitment and nullifier data structures

[Acentelles]

As requested by Arturo and Robert, provide a document that outlines Taiga's requirement for using their Merkle Mountain Belt.

See for context:
https://www.notion.so/heliax/73eb4da6a40849a29336b596aefd5080?v=53b62064a4604f34abf0f74bcd9e2fce&p=10099a579602802e812ef5304990b10a&pm=s