doc txt & -h consistency: add or fix optional "--" syntax

Add the "[--]" for those cases where the *.txt and -h were
inconsistent, or where we incorrectly stated in one but not the other
that the "--" was mandatory.

In the case of "rev-list" both sides were wrong, as we we don't
require one or more paths if "--" is used, e.g. this is OK:

	git rev-list HEAD --

That part of this change is not a "doc txt & -h consistency" change,
as we're changing both versions, doing so here makes both sides
consistent.

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

Documentation/git-rev-list.txt

@@ -9,7 +9,7 @@ git-rev-list - Lists commit objects in reverse chronological order
 SYNOPSIS
 --------
 [verse]
-'git rev-list' [<options>] <commit>... [[--] <path>...]
+'git rev-list' [<options>] <commit>... [--] [<path>...]
 
 DESCRIPTION
 -----------

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> <arguments>"),
+	N_("git for-each-repo --config=<config> [--] <arguments>"),
 	NULL
 };
 

builtin/rev-list.c

@@ -20,7 +20,7 @@
 #include "packfile.h"
 
 static const char rev_list_usage[] =
-"git rev-list [<options>] <commit>... [-- <path>...]\n"
+"git rev-list [<options>] <commit>... [--] [<path>...]\n"
 "\n"
 "  limiting output:\n"
 "    --max-count=<n>\n"

builtin/verify-pack.c

@@ -56,7 +56,7 @@ static int verify_one_pack(const char *path, unsigned int flags, const char *has
 }
 
 static const char * const verify_pack_usage[] = {
-	N_("git verify-pack [-v | --verbose] [-s | --stat-only] <pack>.idx..."),
+	N_("git verify-pack [-v | --verbose] [-s | --stat-only] [--] <pack>.idx..."),
 	NULL
 };