add note about Item.custom_id

discord/ui/item.py

@@ -83,6 +83,8 @@ class Item(Generic[V]):
         self._max_row: int = 5 if not self._is_v2() else 10
 
         if self._is_v2():
+            # this is done so v2 components can be stored on ViewStore._views
+            # and does not break v1 components custom_id property
             self.custom_id: str = os.urandom(16).hex()
 
     def to_component_dict(self) -> Dict[str, Any]: