Update MidiBle.ino

Author: RobertoHE

examples/MidiBle/MidiBle.ino

@@ -4,6 +4,10 @@
 #include <hardware/BLEMIDI_ESP32.h>
 //#include <hardware/BLEMIDI_ArduinoBLE.h>
 
+#ifndef LED_BUILTIN
+#define LED_BUILTIN 2
+#endif
+
 BLEMIDI_CREATE_DEFAULT_INSTANCE()
 
 unsigned long t0 = millis();