Documentation:  "Run your first playbook" shows wrong path

Documentation shows wrong path:
https://github.com/ZPESystems/Ansible
Section "Run your fist playbook" reads:

```
sudo su - ansible
ansible-playbook /etc/ansible/playbooks/ng_get_facts.yml
```

it should read:
```
sudo su - ansible
ansible-playbook /etc/ansible/playbooks/examples/nodegrid/ng_get_facts.yml
```