Update readme.md and add figures to delineate the
relationship of edk2 Redfish, USB NIC and IPMI.
Signed-off-by: Abner Chang <abner.chang@amd.com>
Cc: Nickle Wang <nicklew@nvidia.com>
Cc: Igor Kulchytskyy <igork@ami.com>
Reviewed-by: Nickle Wang <nicklew@nvidia.com>