"docs": Authentication protocol proof -- code correspondence

This CL updates the proof of our mutual authentication protocol
so that it corresponds to the Golang code in
https://vanadium.googlesource.com/release.go.x.ref/+/master/runtime/internal/flow/conn/auth.go

In particular, the protocol formalization in the proof is structured
similar to the code with two key helper functions "setup" and
"readRemoteAuth". Furthermore, following the convention in the code,
all occurrences of the words "client" and "server" are replaced with
"dialer" and "acceptor" respectively.

Change-Id: I40e61b022c3cd8d06abd8a1f9b2b8437298ec7d9
2 files changed