doc txt & -h consistency: add missing options

Change those built-in commands that were attempting to exhaustively
list the options in the "-h" output to actually do so, and always
have *.txt documentation know about the exhaustive list of options.

Let's also fix the documentation and -h output for those built-in
commands where the *.txt and -h output was a mismatch of missing
options on both sides.

In the case of "interpret-trailers" fixing the missing options reveals
that the *.txt version was implicitly claiming that the command had
two operating modes, which a look at the -h version (and studying the
documentation) will show is not the case.

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

builtin/init-db.c

@@ -516,6 +516,8 @@ static int shared_callback(const struct option *opt, const char *arg, int unset)
 
 static const char *const init_db_usage[] = {
 	N_("git init [-q | --quiet] [--bare] [--template=<template-directory>]\n"
+	   "         [--separate-git-dir <git-dir>] [--object-format=<format>]\n"
+	   "         [-b <branch-name> | --initial-branch=<branch-name>]\n"
 	   "         [--shared[=<permissions>]] [<directory>]"),
 	NULL
 };