Updated examples to use globals

examples/buttons.php

@@ -1,6 +1,7 @@
 <?php
 
 require_once __DIR__."/../vendor/autoload.php";
+require_once __DIR__."/GLOBALS.php";
 
 use NoccyLabs\Gpio\Gpio;
 use NoccyLabs\Gpio\GpioMapper\WiringPiMapper;