DBRIS(3pm): document "departure" key for formation requests

Request trip details for I<journeyID>.

The result is available via C<< $status->result >>.

=item B<formation> => B<{> B<eva> => I<eva>, B<train_type> => I<type>, B<train_number> => I<number> B<}>

=item B<formation> => B<{> B<eva> => I<eva>, B<train_type> => I<type>, B<train_number> => I<number>, B<departure> => I<datetime> B<}>

Request carriage formation of train I<type> I<number> at I<eva>.

The result is available via C<< $status->result >>.

Request carriage formation of train I<type> I<number>, scheduled to depart from

I<eva> at I<datetime>. I<eva> is an eva number as returned by, e.g.,

C<< $location->eva >>. The result is available via C<< $status->result >>.

=back