Documentation: auditing cryptography code

[paulmillr]

• Case: a 3rd party, or an auditor you've engaged, wants to audit cryptography code.
• Problem: It takes a long time to understand what's happening and where.
• Solution: prepare the audit trail for them and place it somewhere in readme or docs.

I've prepared one and can submit a PR. Check out the graphs and audit trail: https://gist.github.com/paulmillr/4f268f448d4e4dc31ff99503f6935a29