This adds a clanModule for `mycelium`.
`Mycelium` is an IPv6 overlay network written in Rust.
Each node that joins the overlay network will receive an overlay network IP in the 400::/7 range.
An example configuration might look like this in the inventory:
```nix
mycelium.default = {
roles.peer.machines = [
"berlin"
"munich"
];
config = {
topLevelDomain = "m";
openFirewall = true;
addHostedPublicNodes = true;
};
};
```
This will add the machines named `berlin` and `munich` to the `mycelium` vpn.
And will also set the toplevel domain of the mycelium vpn to `m`, meaning the
machines are now reachable via `berlin.m` and `munich.m`.
