Fix config file instructions for goaccess.

I completely misunderstood the config file location for goaccess.conf.
The config file hasn't moved to ETCDIR, only the sample file has. The
config file is still read from PREFIX/etc.

Remove the UPDATING/pkg-message instructions about this, and install
the config file to the correct place, along with a PORTREVISION bump.

Pointy hat: adamw