help.c: use puts() instead of printf{,_ln}() for consistency

help.c: use puts() instead of printf{,_ln}() for consistency

Change code in "help.c" that used printf_ln() without format
specifiers to use puts() instead, as other existing code in the file
does. Let's also change related code to use puts() instead of the
equivalent of calling "printf" with a "%s\n" format.

This formatting-only change will make a subsequent functional change
easier to read, as it'll be changing code that's consistently using
the same functions to do the same things.

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