Add led example to setup correctly a led

led/led.ino

@@ -0,0 +1,12 @@
+void setup() {
+  // initialize digital pin LED_BUILTIN as an output.
+  pinMode(LED_BUILTIN, OUTPUT);
+}
+
+// the loop function runs over and over again forever
+void loop() {
+  digitalWrite(LED_BUILTIN, HIGH);   // turn the LED on (HIGH is the voltage level)
+  delay(1000);                       // wait for a second
+  digitalWrite(LED_BUILTIN, LOW);    // turn the LED off by making the voltage LOW
+  delay(1000);                       // wait for a second
+}