Add MQTT autodiscovery for HA MQTT Addon

src/run.sh

@@ -1,4 +1,9 @@
-#!/bin/bash
+#!/command/with-contenv bashio
 export IS_HA_ADDON="true"
 
+export MQTTHOST=$(bashio::services mqtt "host")
+export MQTTPORT=$(bashio::services mqtt "port")
+export MQTTUSER=$(bashio::services mqtt "username")
+export MQTTPASS=$(bashio::services mqtt "password")
+
 python -u main.py