Add type to for Link Listener

```
link:
  dialers:
    - binding:          transport
  listeners:
    - binding:          transport
      bind:             tls:127.0.0.1:7878
      advertise:        tls:127.0.0.1:7878

    - binding:          transport
      bind:             tls:127.0.0.1:5876
      advertise:        tls:127.0.0.1:5876
      type: cellular <-----Add this
```