tools/nolibc: drop outdated example from overview comment

This behaviour was changed in commit a7604ba1 ("tools/nolibc/sys:
make open() take a vararg on the 3rd argument").

Signed-off-by: Louis Taylor <louis@kragniz.eu>
Link: https://lore.kernel.org/r/20250306184147.208723-4-louis@kragniz.eu


Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>