Minor doc adjustements for low power mode

docs/use/boards.md

@@ -17,6 +17,10 @@ OpenMQTTGateway support a low power mode for ESP32, this mode can be set by MQTT
 
 `mosquitto_pub -t "home/OpenMQTTGateway/commands/MQTTtoBT/config" -m '{"low_power_mode":2}'`
 
+::: tip
+When coming back from mode 2 to mode 0 you may publish the command with a retain flag so as to enable the gateway to retrieve it when reconnecting.
+:::
+
 ::: warning
 If you change the default low power mode in config_BT.h to 2 and your credential are not set or not correct, the ESP32 will not connect to the broker and the only way to change the low power mode will be a new erase/upload.
 :::
@@ -46,13 +50,13 @@ you can also revert it to the serial monitor:
 `mosquitto_pub -t home/OpenMQTTGateway/commands/MQTTtoM5/config -m '{"log-display":false}'`
 
 ### Low power mode for M5 boards
-OpenMQTTGateway support a low power mode for ESP32, this mode can be set by MQTT on a barebone ESP32:
+OpenMQTTGateway support a low power mode for ESP32, this mode can be set by MQTT or a button on M5 boards:
 
 * Normal mode (per default), screen ON
 
 `mosquitto_pub -t "home/OpenMQTTGateway/commands/MQTTtoBT/config" -m '{"low_power_mode":0}'`
 
-* Low Power mode, screen ON when processing
+* Low Power mode, screen ON when processing only
 
 `mosquitto_pub -t "home/OpenMQTTGateway/commands/MQTTtoBT/config" -m '{"low_power_mode":1}'`