anchor.diff:  
   1. You can enable notifications by e-mail, PagerDuty, AWS CloudWatch, DataDog, OpenTSDB, and Graphite. Follow the instructions below for the appropriate plugin.
   
  -###<a id='email'></a> Configure E-Mail
  +###<a id='email'></a> Configure Email
   
   <%= vars.email_notifications %>
   
  
positive.code: * `user`: If you set `auth` to `plain`, provide the username for SMTP authentication.
  * `password`: If you set `auth` to `plain`, provide the password for SMTP authentication.
  
  To customize the contents of your notification e-mail, see the [Getting Started with the Notifications Service](notifications.html) topic.
  
  ###<a id='pagerduty'></a> Configure PagerDuty
  
  
negative.code: * `datadog_enabled`: Set to `true`.
  * `datadog.api_key`: Provide the API key for DataDog. For more information about DataDog, see the [DataDog documentation](http://docs.datadoghq.com/api/).
  * `datadog.application_key`: Provide the HM application key for DataDog.
  * `datadog.pagerduty_service_name`: Provide the service name to alert in PagerDuty on HM events.
  