Updated doc.

Author: s3rius

Doc/c-api/module.rst

@@ -92,14 +92,14 @@ Module Objects
 
 .. c:function:: void* PyModule_GetState(PyObject *module)
 
-   Return the "state" of the module, that is, a pointer to the block of memory
-   allocated at module creation time, or ``NULL``.
+   The module’s state can be stored in per‑module memory, which is obtained by calling this function.
+   This makes modules safe to use with sub‑interpreters.
 
-   Takes a pointer to a modlue as an argument.
-
-   See
-   :c:member:`PyModuleDef.m_size`.
+   The amount of memory allocated for the module’s state is specified by the :c:member:`PyModuleDef.m_size` field.
 
+   The function returns a pointer to the state memory, or **NULL**
+   if the argument is not a `PyModule` object or
+   if the module does not support local state (i.e., :c:member:`PyModuleDef.m_size` is ``-1``).
 
 .. c:function:: PyModuleDef* PyModule_GetDef(PyObject *module)