efl_ui: docuement code

there was the request that this needs to be documented, here we are.

Reviewed-by: Cedric BAIL <cedric.bail@free.fr>
Differential Revision: https://phab.enlightenment.org/D10874

src/lib/elementary/efl_ui_collection.c

@@ -438,6 +438,7 @@ _efl_ui_collection_efl_object_invalidate(Eo *obj, Efl_Ui_Collection_Data *pd EIN
    while(pd->items)
      efl_del(pd->items->data);
 
+   // pan is given to edje, which reparents it, which forces us to manually deleting it
    efl_del(pd->pan);
 
    efl_invalidate(efl_super(obj, MY_CLASS));

src/lib/elementary/efl_ui_collection_view.c

@@ -2072,6 +2072,7 @@ _efl_ui_collection_view_efl_object_invalidate(Eo *obj,
 
    _all_cleanup(obj, pd);
 
+   //pd pan is given to edje, which reparents it, which forces us to manually deleting it
    if (pd->pan)
      efl_del(pd->pan);
 

src/lib/elementary/efl_ui_scroller.c

@@ -281,6 +281,7 @@ _efl_ui_scroller_efl_object_finalize(Eo *obj,
 EOLIAN static void
 _efl_ui_scroller_efl_object_invalidate(Eo *obj, Efl_Ui_Scroller_Data *pd)
 {
+   // pan is given to edje, which reparents it, which forces us to manually deleting it
    efl_event_callback_del(pd->pan_obj, EFL_GFX_ENTITY_EVENT_SIZE_CHANGED,
                           _efl_ui_scroller_pan_resized_cb, obj);
    efl_del(pd->pan_obj);