bpo-40348: Fix typos in the programming FAQ (GH-19729)

(cherry picked from commit caf1aad)

Co-authored-by: Zackery Spytz <zspytz@gmail.com>

Author: miss-islington

Diff for: Doc/faq/programming.rst

@@ -1494,8 +1494,8 @@ to uppercase::
 
 Here the ``UpperOut`` class redefines the ``write()`` method to convert the
 argument string to uppercase before calling the underlying
-``self.__outfile.write()`` method.  All other methods are delegated to the
-underlying ``self.__outfile`` object.  The delegation is accomplished via the
+``self._outfile.write()`` method.  All other methods are delegated to the
+underlying ``self._outfile`` object.  The delegation is accomplished via the
 ``__getattr__`` method; consult :ref:`the language reference <attribute-access>`
 for more information about controlling attribute access.