Add documentation on how to define locations to monitor.

playbooks/roles/jenkins_admin/tasks/nat_monitor.yml

 ---
+# Nat monitors should be defined as a list of dictionaries
+# e.g.
+# NAT_MONITORS:
+#   - vpc_name: 'loadtest-edx'
+#     region: 'us-east-1'
+#     deployment: 'edx'
+# 
+# To receive E-mails, ses should be setup with the
+# aws account that is defined by the JENKINS_ADMIN_MAIL_PROFILE
+# and the from adress should be verified
+# JENKINS_ADMIN_MAIL_PROFILE: 'aws_account_name'
+# JENKINS_ADMIN_FROM_EMAIL: 'admin@example.com'
+# JENKINS_ADMIN_TO_EMAIL: 'alert@example.com'
+
+
 - fail: msg="NAT_MONITORS is not defined."
   when: NAT_MONITORS is not defined