Fix help message in pg_ctl.

Previously the help message described that -m is an option for
"stop", "restart" and "promote" commands in pg_ctl. But actually
that's not an option for "promote". So this commit fixes that
incorrect description in the help message.

Back-patch to 9.3 where the incorrect description was added.

src/bin/pg_ctl/pg_ctl.c

@@ -1905,7 +1905,7 @@ do_help(void)
 	printf(_("  -o OPTIONS             command line options to pass to postgres\n"
 	 "                         (PostgreSQL server executable) or initdb\n"));
 	printf(_("  -p PATH-TO-POSTGRES    normally not necessary\n"));
-	printf(_("\nOptions for stop, restart, or promote:\n"));
+	printf(_("\nOptions for stop or restart:\n"));
 	printf(_("  -m, --mode=MODE        MODE can be \"smart\", \"fast\", or \"immediate\"\n"));
 
 	printf(_("\nShutdown modes are:\n"));