gh-121403: Add notes for PyList_GetXXX APIs about the need for init

Author: corona10

Doc/c-api/list.rst

@@ -65,17 +65,29 @@ List Objects
 
    .. versionadded:: 3.13
 
+   .. note::
+      You can not use this function until all items are set to real objects
+      with :c:func:`PyList_SetItem` or :c:func:`PyList_SET_ITEM`.
+
 
 .. c:function:: PyObject* PyList_GetItem(PyObject *list, Py_ssize_t index)
 
    Like :c:func:`PyList_GetItemRef`, but returns a
    :term:`borrowed reference` instead of a :term:`strong reference`.
 
+   .. note::
+      You can not use this function until all items are set to real objects
+      with :c:func:`PyList_SetItem` or :c:func:`PyList_SET_ITEM`.
+
 
 .. c:function:: PyObject* PyList_GET_ITEM(PyObject *list, Py_ssize_t i)
 
    Similar to :c:func:`PyList_GetItem`, but without error checking.
 
+   .. note::
+      You can not use this function until all items are set to real objects
+      with :c:func:`PyList_SetItem` or :c:func:`PyList_SET_ITEM`.
+
 
 .. c:function:: int PyList_SetItem(PyObject *list, Py_ssize_t index, PyObject *item)