Description of IPv6 Prefix Delegation driver configuration options

Configuration option = Default value	Description
[DEFAULT]
pd_confs = $state_path/pd	(StrOpt) Location to store IPv6 PD files.
pd_dhcp_driver = dibbler	(StrOpt) Service to handle DHCPv6 Prefix delegation.
vendor_pen = 8888	(StrOpt) A decimal value as Vendor's Registered Private Enterprise Number as required by RFC3315 DUID-EN.