[reSIProcate] TLS auth matrix

[Daniel Pocock]

I've prepared a table listing various permutations of DIGEST and TLS auth:

  https://www.resiprocate.org/TLSAuthentication#Analysis

This may be helpful for understanding the impact of these repro.config
options:

DisableAuth = true | false
EnableCertificateAuthenticator = true | false
TLSClientVerification = None | Optional | Mandatory