Update documentation docs/libvirt.md

[sukucorp]

In "Install Windows" section, when loading drivers for VirtIO, also load the drivers for NetKVM. This will allow Windows to detect the network in the next step. Refer to the following installation guide for details https://sysguides.com/install-a-windows-11-virtual-machine-on-kvm.

[AkechiShiro]

Thanks for bringing this issue to us, pulling netKVM during installation will allow some more features to be enabled/installed in the Windows VM by default ?