Document PyException_HEAD

Author: ZeroIntensity

Doc/c-api/exceptions.rst

@@ -793,6 +793,17 @@ Exception Classes
    Return :c:member:`~PyTypeObject.tp_name` of the exception class *ob*.
 
 
+.. c:macro:: PyException_HEAD
+
+   This is a :term:`soft deprecated` macro including the base fields for an
+   exception object.
+
+   This was included in Python's C API by mistake and is not designed for use
+   in extensions. For creating custom exception objects, use
+   :c:func:`PyErr_NewException` or otherwise create a class inheriting from
+   :c:data:`PyExc_BaseException`.
+
+
 Exception Objects
 =================