reorder overloads; add comment

Author: xavdid

stdlib/builtins.pyi

@@ -784,10 +784,12 @@ class slice:
     def indices(self, __len: SupportsIndex) -> tuple[int, int, int]: ...
 
 class tuple(Sequence[_T_co], Generic[_T_co]):
-    @overload
-    def __new__(cls) -> tuple[()]: ...
+    # overloads are ordered this way to pass `isinstance` checks
+    # see: https://github.com/python/typeshed/pull/7454#issuecomment-1061490888
     @overload
     def __new__(cls: type[Self], __iterable: Iterable[_T_co]) -> Self: ...
+    @overload
+    def __new__(cls) -> tuple[()]: ...
     def __len__(self) -> int: ...
     def __contains__(self, __x: object) -> bool: ...
     @overload