event: Fix ButtonEvent docstring

panda/src/event/buttonEvent.h

@@ -46,17 +46,18 @@ class DatagramIterator;
 class EXPCL_PANDA_EVENT ButtonEvent {
 public:
   enum Type {
-/*
- * T_down and T_up represent a button changing state correspondingly.
- * T_resume_down is a special event that is only thrown when focus is returned
- * to a window and a button is detected as being held down at that point; it
- * indicates that the button should be considered down now (if it wasn't
- * already), but it didn't just get pressed down at this moment, it was
- * depressed some time ago.  It's mainly used for correct tracking of modifier
- * keys like shift and control, and can be ignored for other keys.
- */
+    // T_down is sent when a button was just pressed.
     T_down,
+
+    // T_resume_down is a special event that is only thrown when focus is
+    // returned to a window and a button is detected as being held down at that
+    // point; it indicates that the button should be considered down now (if it
+    // wasn't already), but it didn't just get pressed down at this moment, it
+    // was depressed some time ago.  It's mainly used for correct tracking of
+    // modifier keys like shift and control, and can be ignored for other keys.
     T_resume_down,
+
+    // T_down is sent when a button is released.
     T_up,
 
     // T_repeat is sent for each a keyrepeat event generated by the system,