Followup to 4c59cd84086f: add an entry in the porting guide and a "versionchanged" attribute.

Doc/c-api/init.rst

@@ -537,10 +537,11 @@ code, or when embedding the Python interpreter:
    operations such as ``PyEval_ReleaseThread(tstate)``. It is not needed before
    calling :c:func:`PyEval_SaveThread` or :c:func:`PyEval_RestoreThread`.
 
-   .. index:: single: Py_Initialize()
-
    This is a no-op when called for a second time.
 
+   .. versionchanged:: 3.2
+      This function cannot be called before :c:func:`Py_Initialize()` anymore.
+
    .. index:: module: _thread
 
    .. note::

Doc/whatsnew/3.2.rst

@@ -2698,3 +2698,7 @@ require changes to your code:
   a new function, :func:`asyncore.handle_accepted`, was added to replace it.
 
   (Contributed by Giampaolo Rodola in :issue:`6706`.)
+
+* Due to the new :term:`GIL` implementation, :c:func:`PyEval_InitThreads()`
+  cannot be called before :c:func:`Py_Initialize()` anymore.
+