mod_auth_ccert/README: Add setting to ensure Prosdy asks for client certificate This used to be the default for all services, but since it triggers annoying popups in web browsers it was inverted in Prosody and only s2s enables it, so it needs to be explicitly enabled for c2s again. See trunk 115b5e32d960 Thanks debacle

This module writes out a traceback to `traceback.txt` in Prosodys data
directory (see `prosodyctl about`) when the signal `SIGUSR1` is
received. This is useful when debugging seemingly frozen instances in
case it is stuck in Lua code.