'git push -h' shows usage text with incomplete list of options and then
has a separate list of options that are supported. Imitate the way other
commands (I looked at 'git diff' for an example) show their options.
Signed-off-by: しらいし ななこ <nanako3@lavabit.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>