Does -net user still do anything useful with VLAN gone? Let's take a step back and consider: what's left of -net with VLAN gone? I guess it's just -net none and -net nic,netdev=...
If that's true, the documentation for the backend types user, ... needs to move to -netdev. Since we're breaking -net anyway, why not kill it dead: move "none" to -netdev, and drop -net nic in favour of -device.
