gh-151788: Fix NEWS entry doc reference

Drop the :meth: cross-reference to list_directory, which is not a
documented method and fails the docs "new NEWS nits" check.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: mjbommar

Misc/NEWS.d/next/Library/2026-06-20-09-00-26.gh-issue-151788.Gr8IxK.rst

@@ -1,5 +1,4 @@
 :class:`http.server.SimpleHTTPRequestHandler` now uses :func:`os.scandir`
 instead of :func:`os.listdir` to build directory listings, avoiding an
-:func:`os.stat` call per entry. This can improve
-:meth:`~http.server.SimpleHTTPRequestHandler.list_directory` performance where
-``stat`` calls are slow.
+:func:`os.stat` call per entry. This can improve directory listing performance
+where ``stat`` calls are slow.