Clarify how the controller-state demo works

I think the description of this sample was a bit confusing. It would be natural to expect the pointed-at box to change color, but it's actually showing one box per button and toggles color independent of the pointing direction.

Author: klausw

controller-state.html

@@ -36,9 +36,9 @@
       <details open>
         <summary>Controller State</summary>
         <p>
-          This sample demonstrates using XRInputSource Gamepad button presses
-          to change box color and joystick/touchpad input to move boxes in 2
-          dimensions.
+          This sample demonstrates XRInputSource Gamepad integration. It shows 
+          one box per available button. Pressing the button toggles the associated 
+          box's color. Use joystick/touchpad input to move boxes in 2 dimensions.
           <a class="back" href="./index.html">Back</a>
         </p>
       </details>
@@ -364,4 +364,4 @@
       initXR();
     </script>
   </body>
-</html>
+</html>