Remove deprecated --max-routes option from manual

Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <1406237866-9086-1-git-send-email-arne@rfc2549.org>
URL: http://article.gmane.org/gmane.network.openvpn.devel/8938

Signed-off-by: Gert Doering <gert@greenie.muc.de>