doc txt & -h consistency: use "git foo" form, not "git-foo"

doc txt & -h consistency: use "git foo" form, not "git-foo"

Use the "git cmd" form instead of "git-cmd" for both "git
receive-pack" and "git credential-cache--daemon".

For "git-receive-pack" we do have a binary with that name, even when
installed with SKIP_DASHED_BUILT_INS=YesPlease, but for the purposes
of the SYNOPSIS let's use the "git cmd" form like everywhere else. It
can be invoked like that (and our tests do so), the parts of our
documentation that explain when you need to use the dashed form do so,
and use it.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>