Setup public_ip before install

[elekjani]

Hi Sonatas,

I'm trying to setup a working sonata platform with these install script and as I understand there is a "secret" public_ip variable that one should change to the public IP of the host. It would be great if you can include this in the README.md.

Some info:
Master branch, commit a97ad93
Files:
install/group_vars/all, install/roles/docker/files/group_vars.all
Ansible command:
ansible-playbook son-cmud.yml -e "target=localhost env=demo operation=install service=all"

Regards,
Janos