Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1205 This patch is to add the driver usage/difference clarification compared to UefiPxeBcDxe in NetworkPkg. Cc: Ye Ting <ting.ye@intel.com> Cc: Fu Siyuan <siyuan.fu@intel.com> Cc: Laszlo Ersek <lersek@redhat.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Wu Jiaxin <jiaxin.wu@intel.com> Reviewed-by: Laszlo Ersek <lersek@redhat.com>