[3.15] gh-114150: Clarify that ctypes.PYFUNCTYPE can release the GIL during the call (GH-114151) (GH-159734)

(cherry picked from commit d42178a)

Co-authored-by: arrmansa <41120982+arrmansa@users.noreply.github.com>
Co-authored-by: Peter Bierma <zintensitydev@gmail.com>

Author: 3 people

Doc/library/ctypes.rst

@@ -2006,7 +2006,11 @@ See :ref:`ctypes-callback-functions` for examples.
 .. function:: PYFUNCTYPE(restype, *argtypes)
 
    The returned function prototype creates functions that use the Python calling
-   convention.  The function will *not* release the GIL during the call.
+   convention.  Unlike :func:`CFUNCTYPE` and :func:`WINFUNCTYPE`, ctypes does
+   *not* release the GIL before calling the foreign function, so the function
+   may safely use the Python C API. Note that this does not prevent the GIL
+   from being released *during* the call.
+
 
 Function prototypes created by these factory functions can be instantiated in
 different ways, depending on the type and number of the parameters in the call: