Hide DAL.x behind Enum

docs/reference/led/enable.md

@@ -15,7 +15,7 @@ led.enable(false);
 This program turns off the screen when pressing button ``B``
 
 ```blocks
-input.input.onButtonEvent(Button.B, DAL.MICROBIT_BUTTON_EVT_CLICK, () => {
+input.input.onButtonEvent(Button.B, ButtonEvent.Click, () => {
     led.enable(false)
 });
 ```

docs/reference/led/stop-animation.md

@@ -13,7 +13,7 @@ This program sets up the ``stop animation`` part of the program,
 and then shows a string that you can stop with button ``B``.
 
 ```blocks
-input.input.onButtonEvent(Button.B, DAL.MICROBIT_BUTTON_EVT_CLICK, () => {
+input.input.onButtonEvent(Button.B, ButtonEvent.Click, () => {
     led.stopAnimation();
 });
 basic.showString("STOP ME! STOP ME! PLEASE, WON'T SOMEBODY STOP ME?");