Add message on LEDs when entering setup mode

LibreMetric.ino

@@ -45,6 +45,9 @@ String message, webpage;
 ESP8266WebServer server(PORT);
 Max72xxPanel matrix = Max72xxPanel(pinCS, numberOfHorizontalDisplays, numberOfVerticalDisplays);
 
+void configModeCallback (WiFiManager *myWiFiManager) { // AP config mode
+  display_static_message("Setup");
+}
 
 void setup() {
   Serial.begin(115200); // initialize serial communications
@@ -62,10 +65,14 @@ void setup() {
   display_static_message("Wi-Fi");
 
   WiFiManager wifiManager;
+  // reset saved settings
+  // wifiManager.resetSettings();
+
 #ifndef DEBUG_WifiM
   wifiManager.setDebugOutput(false); // no debug
 #endif
   wifiManager.setTimeout(180);
+  wifiManager.setAPCallback(configModeCallback);
   if(!wifiManager.autoConnect("LibreMetric")) {
     DEBUG_PRINTLN(F("failed to connect and timeout occurred"));
     display_static_message("No OK");