Fix to --shaper documentation on the man-page

Trac: #413
Trac-URL: https://community.openvpn.net/openvpn/ticket/413
Signed-off-by: Samuli Seppänen <samuli@openvpn.net>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <1416564585-14546-1-git-send-email-samuli@openvpn.net>
URL: http://article.gmane.org/gmane.network.openvpn.devel/9254
Signed-off-by: Gert Doering <gert@greenie.muc.de>