[DISC] Add runtime configuration for OpenHAB (#1658)

* [DISC] Add runtime configuration for OpenHAB

Add an MQTT configurable system key "ohdiscovery" for OpenHAB auto discovery

* Docs and environments update

docs/integrate/openhab3.md

@@ -64,7 +64,7 @@ Bravo👏, second step done! Now let's add the Jinja transformation service.
 Second step done!
 
 ## Upload OpenMQTTGateway to an ESP32
-[Upload OpenMQTTGateway from the web](../upload/web-install.md) by selecting `esp32dev-ble-openhab`
+[Upload OpenMQTTGateway from the web](../upload/web-install.md) by selecting the environment corresponding to your need.
 
 Or use another upload method from the Upload section.
 
@@ -75,6 +75,10 @@ Or use another upload method from the Upload section that requires credentials b
 
 You should see the gateway connected to your broker by checking with an MQTT client like MQTT Explorer.
 
+To make the auto discovery compatible with OpenHAB you have to send the following command with a retain flag.
+
+`mosquitto_pub -t "home/OpenMQTTGateway/commands/MQTTtoSYS/config" -m '{"ohdiscovery":true}'`
+
 ## Adding the things
 1. From the Administration click on "Things" under "Settings", you should see a number in the INBOX button