Add example of registering events not part of an array

src/main.c

@@ -30,6 +30,7 @@ enum event_ids {
 void window_event_handler(void *data);
 void keyboard_event_handler(void *data);
 void mouse_event_handler(void *data);
+void extra_event_handler(void *data);
 
 int main(void) {
   Event         events   [COUNT_EVENTS] = {0};
@@ -59,6 +60,13 @@ int main(void) {
   printf("    X: %d, Y: %d\n", mouse_event.x, mouse_event.y);
   es_emit_event(es, events[EVENT_MOUSE],    (void *)&mouse_event);
 
+  // You can also add other events not stored in an array
+  Event         extra_event = es_register_event(es);
+  EventListener listener    = es_add_event_listener(es, extra_event, extra_event_handler);
+  es_emit_event(es, extra_event, NULL);
+  es_remove_event_listener(es, listener);
+  es_deregister_event(es, extra_event);
+
   for (int i = 0; i < COUNT_EVENTS; ++i) {
     es_remove_event_listener(es, listeners[i]);
     es_deregister_event(es, events[i]);
@@ -101,3 +109,7 @@ void mouse_event_handler(void *data) {
   printf("FROM CALLBACK\n");
   printf("    X: %d, Y: %d\n\n", ev->x, ev->y);
 }
+
+void extra_event_handler(void *data) {
+  printf("Calling extra_event_handler\n\n");
+}