Minor man page improvement.
Moritz von Schweinitz suggests:
I was suggesting more something along the lines of 'By default, tor will only act as a client. If you want to help us by providing server and relay functionality, please read https://www.torproject.org/docs/faq-abuse.html.en and change the ORPort parameter.' In the description part of the man page.
to make it more obvious when a tor instance becomes a relay and how to run a relay.