Update readme

Author: robmarkcole

adds-leak-sensor/README.md

@@ -2,4 +2,11 @@ Adds an analogue leak sensor, a dirt cheap (£1.26) sensor.
 
 Sensor: https://www.amazon.co.uk/gp/product/B00K67Z76O/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1
 
+Add to [home-assistant](https://home-assistant.io/) using an mqtt [binary sensor](https://home-assistant.io/components/binary_sensor.mqtt/):
+```
+- platform: mqtt
+  name: "Wipy water monitor"
+  state_topic: "bme680-water"
+```
+
 <img src="https://github.com/robmarkcole/bme680-mqtt-micropython/blob/master/adds-leak-sensor/BME-680%2Bleak.JPG">