Update torrc.sample.in to IPv6Exit 1 being an exit by default

## Uncomment this if you want your relay to be an exit, with the default

## exit policy (or whatever exit policy you set below).

## (If ReducedExitPolicy or ExitPolicy are set, relays are exits.

## (If ReducedExitPolicy, ExitPolicy, or IPv6Exit are set, relays are exits.

## If neither exit policy option is set, relays are non-exits.)

#ExitRelay 1

## Uncomment this if you want your relay to allow IPv6 exit traffic.

## You must also set ExitRelay, ReducedExitPolicy, or ExitPolicy to make your

## relay into an exit.

## (Relays do not allow any exit traffic by default.)

#IPv6Exit 1