nerdbox network on linux

[ningmingxiao]

I find "External network providers " https://github.com/containerd/nerdbox/blob/main/docs/vm-configuration.md only support on macos.
can we provide some doc about how to use on linux @akerouanton

[akerouanton]

@ningmingxiao containers/gvisor-tap-vsock is cross-platform and I assume passt works on Linux (although I didn't it).