Update os.fwalk docstrings

Author: totosuki

Lib/os.py

@@ -460,13 +460,13 @@ def fwalk(top=".", topdown=True, onerror=None, *, follow_symlinks=False, dir_fd=
         Example:
 
         import os
-        for root, dirs, files, rootfd in os.fwalk('python/Lib/email'):
+        for root, dirs, files, rootfd in os.fwalk('python/Lib'):
             print(root, "consumes", end="")
             print(sum(os.stat(name, dir_fd=rootfd).st_size for name in files),
                   end="")
             print("bytes in", len(files), "non-directory files")
-            if 'CVS' in dirs:
-                dirs.remove('CVS')  # don't visit CVS directories
+            if '__pycache__' in dirs:
+                dirs.remove('__pycache__')  # don't visit __pycache__ directories
         """
         sys.audit("os.fwalk", top, topdown, onerror, follow_symlinks, dir_fd)
         top = fspath(top)