Update README.md

README.md

@@ -23,6 +23,8 @@ Collect the following information:
 1. MQTT server information: hostname, username, password
     1. If using TLS, define `MQTT_PORT` and `MQTT_TLS=true`
     1. **NEW! - Provide MQTT topic (MQTT_ONSTAR_POLLING_STATUS_TOPIC) for Onstar Data Polling Status to monitor success/failure when OnStar is polled for data**
+       * MQTT_ONSTAR_POLLING_STATUS_TOPIC/lastpollsuccessful - "true" or "false" depending on status of last poll
+       * MQTT_ONSTAR_POLLING_STATUS_TOPIC/state - Polling Status and Detailed Error Messages in JSON
 
 Supply these values to the ENV vars below. The default data refresh interval is 30 minutes and can be overridden with ONSTAR_REFRESH with values in milliseconds.