This is mostly the same as the Desktop guide - but with a tiny touch for the headless component.
sudo apt update && sudo apt install -y syncthing
sudo systemctl enable syncthing@jedi.service && \
sudo systemctl start syncthing@jedi.service
nano /home/jedi/.local/state/syncthing/config.xml
nano /home/jedi/.config/syncthing/config.xml
sudo systemctl restart syncthing@username.service
first login will warn about username/password - add them