first addition of a 'how-to'

roles/nhc/README.md

+Creates Node Health Check on a compute node
+see ://github.com/mej/nhc  
+
+It needs some variable to be defined before calling
+
+i.e.
+nhc_version: 1.4.2
+nhc_dir: /opt/nhc-{{ nhc_version }}
+nhc_config_file: nhc.conf
+nhc_log_level: 0
+nhc_emails: nobody@nowhere.nowhere
+nhc_email_subject: "Node Health Check" 
+
+In addition the NAT check needs two variables to be defined to be enabled  (See example)
+
+Example:
+  roles:
+  - { role: nhc, EXTERNAL_IP_ADDRESS: "118.138.246.208", ADD_NHC_NAT_CHECK: 1  }