efa-m: add -O/--output to documentation

Ignore departures which are less than I<minutes> from now.

=item B<-O>, B<--output> I<outputtypes>

For each result, show additional information as specified by I<outputtypes>.

I<outputtypes> is a comma-separated list, the B<-O>/B<--output> option may

also be repeated. Each output type has both a short and long form, for instance

both "-Or" and "--output=route" are valid.

The following output types are supported:

=over

=item a / route_after

Show each departure's full route (timestamps and stop names) after the

requested station.

=item b / route_before

Show each departure's full route (timestamps and stop names) before the

requested station.

=item f / fullroute

Show each departure's full route (timestamps and stop names) before and

after the requested station.

=item r / route

Show up to three stops between the requested station and the departure's

destination. B<efa-m> tries to display the three most important stops,

however these are heuristically determined and may not be optimal.

=back

=item B<-p>, B<--platform> I<platforms>

Only show departures at I<platforms> (comma-separated list, option may be