wiki docs on DNCP outdated

I think that docs https://github.com/hermit-os/hermit-rs/wiki/Advanced-Configuration-Features#dhcp-support outdated. Cargo.toml configuration right now according to examples, looks a bit different.

```Cargo.toml
[target.'cfg(target_os = "hermit")'.dependencies]
hermit = "0.9"

[features]
default = ["hermit/pci", "hermit/tcp", "hermit/dhcpv4"]
```