Make BUTTON_PRESS capitalized

Author: Jenny Plunkett

Flow-Control/Busy-Wait-Button/main.cpp

@@ -3,11 +3,11 @@
 DigitalIn button(SW1); // Change to match your board
 DigitalOut led(LED1);
 
-#define button_press 0
+#define BUTTON_PRESS 0
 
 int main() {
     while(1) {
-        if(button_press == button){
+        if(BUTTON_PRESS == button){
            led = !led;
            wait(1);
        }