net/vmxnet3: update NIC documentation
net/vmxnet3: update NIC documentation

Signed-off-by: Yong Wang <0cd1be787884a033c98e298059e386114d22793e@vmware.com>
Acked-by: Stephen Hemminger <06fa905d7f2aaced6dc72e9511c71a2a51e8aead@networkplumber.org>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk