doc: fix missing note on UIO module in Linux guide

The docs on binding drivers was updated as part of the removal of the
igb_uio module from the main DPDK repo. As part of that update, a note
about uio_pci_generic requiring legacy interrupts was removed, but
should have been kept.

Fixes: 56bb584 ("kernel/linux: remove igb_uio")
Cc: stable@dpdk.org

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>

doc/guides/linux_gsg/linux_drivers.rst

@@ -174,6 +174,11 @@ It can be loaded as shown below:
    sudo modprobe uio
    sudo insmod igb_uio.ko
 
+.. note::
+
+    For some devices which lack support for legacy interrupts, e.g. virtual function
+    (VF) devices, the ``igb_uio`` module may be needed in place of ``uio_pci_generic``.
+
 .. note::
 
    If UEFI secure boot is enabled,