Add build options and guidance doc.
Initialize pci device access for Wangxun Gigabit Ethernet devices.
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Signed-off-by: NMengyuan Lou <mengyuanlou@net-swift.com>
Link: https://lore.kernel.org/r/20220826034609.51854-1-mengyuanlou@net-swift.comSigned-off-by: NPaolo Abeni <pabeni@redhat.com>