doc txt & -h consistency: fix mismatching labels

Fix various inconsistencies between command SYNOPSIS and the
corresponding -h output where our translatable labels didn't match
up.

In some cases we need to adjust the prose that follows the SYNOPSIS
accordingly, as it refers back to the changed label.

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

builtin/for-each-repo.c

@@ -6,7 +6,7 @@
 #include "string-list.h"
 
 static const char * const for_each_repo_usage[] = {
-	N_("git for-each-repo --config=<config> <command-args>"),
+	N_("git for-each-repo --config=<config> <arguments>"),
 	NULL
 };