Update docker setup example hook

[nickhammond]

Thought this might be a nice addition to help people a little bit when getting a new server up and running.

This is specifically for Ubuntu and adds some default UFW rules and a basic fail2ban install.

$ .kamal/hooks/docker-setup
Running 'ufw allow ssh &&   ufw allow http &&   ufw allow https &&   ufw --force enable &&   apt-get install fail2ban -y &&   systemctl start fail2ban &&   systemctl enable fail2ban' on 867.53.0.9...
  INFO [e818ecd1] Running ufw allow ssh &&   ufw allow http &&   ufw allow https &&   ufw --force enable &&   apt-get install fail2ban -y &&   systemctl start fail2ban &&   systemctl enable fail2ban on 867.53.0.9
  INFO [e818ecd1] Finished in 2.468 seconds with exit status 0 (successful).