Update os.walk docstrings

Author: totosuki

Lib/os.py

@@ -345,12 +345,12 @@ def walk(top, topdown=True, onerror=None, followlinks=False):
 
     import os
     from os.path import join, getsize
-    for root, dirs, files in os.walk('python/Lib/email'):
+    for root, dirs, files in os.walk('python/Lib'):
         print(root, "consumes ")
         print(sum(getsize(join(root, name)) 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.walk", top, topdown, onerror, followlinks)