Fix some doc issues

docs/device/reactive.md

@@ -142,7 +142,7 @@ Through this example, we have seen that the micro:bit scheduler enables you to c
 As a result, you can easily add a new capability to the micro:bit by just adding a new subprogram. For example, if you want to add a reset feature to the counter program, all you need to do is add a new event handler for a press of button B that sets the global variable "count" to zero, as shown below:
 
 ```typescript
-export function countButtonPressesWithReset() {
+function countButtonPressesWithReset() {
     let count = 0
     input.onButtonPressed(Button.A, () => {
         count = count + 1