Start and Enable the Systemd Tang Socket

Start and enable the Tang socket so that incoming connections can access the Tang server.
```
sudo systemctl enable --now tangd.socket
```
The Tang process runs when a client connects to the configured socket.
Verify that the Tang socket is started and enabled.
```
sudo systemctl status tangd.socket
```
The output must display that the socket is active and listening.

If you haven't initialized Tang signing keys, do this now so that the Tang service can advertise these signing keys on the network. See Initialize Tang Signing Keys for more information.