configs/agents.conf.sample - Remove example for non-functional "goodbye" parameter

The "goodbye" parameter is not implemented in the source code, it does nothing.

(closes issue SWP-6518)
Reported By: Steve Pitts


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/1.8@408020 f38db490-d61c-443f-a65b-d21fe96a405b