mailinfo: add '--scissors' to usage message

Signed-off-by: Nicolas Sebrecht <nicolas.s.dev@gmx.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-mailinfo.c

@@ -1004,7 +1004,7 @@ static int git_mailinfo_config(const char *var, const char *value, void *unused)
 }
 
 static const char mailinfo_usage[] =
-	"git mailinfo [-k] [-u | --encoding=<encoding> | -n] msg patch <mail >info";
+	"git mailinfo [-k] [-u | --encoding=<encoding> | -n] [--scissors] msg patch < mail >info";
 
 int cmd_mailinfo(int argc, const char **argv, const char *prefix)
 {