closes bpo-33202: fix os.walk mentioning os.listdir instead of os.scandir (GH-6335)

(cherry picked from commit badb894b)
Co-authored-by: Andrés Delfino <34587441+andresdelfino@users.noreply.github.com>

Doc/library/os.rst

@@ -2812,7 +2812,7 @@ features:
    no effect on the behavior of the walk, because in bottom-up mode the directories
    in *dirnames* are generated before *dirpath* itself is generated.
 
-   By default, errors from the :func:`listdir` call are ignored.  If optional
+   By default, errors from the :func:`scandir` call are ignored.  If optional
    argument *onerror* is specified, it should be a function; it will be called with
    one argument, an :exc:`OSError` instance.  It can report the error to continue
    with the walk, or raise the exception to abort the walk.  Note that the filename