[SYS] Publish the reboot reason with retain flag (#1802)

So as to have the information stored on the MQTT broker
Also remove stopProcessing, not necessary as we follow by a restart

main/User_config.h

@@ -697,6 +697,7 @@ Adafruit_NeoPixel leds2(ANEOPIX_IND_NUM_LEDS, ANEOPIX_IND_DATA_GPIO2, ANEOPIX_IN
 #define TimeLedON                    1 // time LED are ON
 #define InitialMQTTConnectionTimeout 10 // time estimated (s) before the board is connected to MQTT
 #define subjectSYStoMQTT             "/SYStoMQTT" // system parameters
+#define subjectLOGtoMQTT             "/LOGtoMQTT" // log informations
 #define subjectRLStoMQTT             "/RLStoMQTT" // latest release information
 #define subjectMQTTtoSYSset          "/commands/MQTTtoSYS/config"
 #define subjectMQTTtoSYSupdate       "/commands/MQTTtoSYS/firmware_update"