message: Added readme for alerting or error.
diff: @@ -134,3 +134,6 @@ stored in the repository.
  ## Alerting
  We are using [elastalert](https://github.com/Yelp/elastalert) plugin to send email alerts on production failures and errors. The plugin scans data from elasticsearch and looks for anomalies/patterns/spikes. Checkout the [documentation](http://elastalert.readthedocs.io/en/latest/) for creating new alert rules.
  +
  +### Alerting on Error
  +To receive service side error alerts, just print the error message in console using `winston.error('message')`. Elastalert aggregates all error messages for last hour and sends an email. Kibana dashboard can also be filtered down to just error messages (search for 'level:error').
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