bpo-40982: shutil docs: Remove outdated copytree() example (GH-24778)

It is not preferable to keep a copy of the implementation in the
docs.
(cherry picked from commit e06f920)

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

Author: miss-islington

Doc/library/shutil.rst

@@ -470,42 +470,7 @@ file then shutil will silently fallback on using less efficient
 copytree example
 ~~~~~~~~~~~~~~~~
 
-This example is the implementation of the :func:`copytree` function, described
-above, with the docstring omitted.  It demonstrates many of the other functions
-provided by this module. ::
-
-   def copytree(src, dst, symlinks=False):
-       names = os.listdir(src)
-       os.makedirs(dst)
-       errors = []
-       for name in names:
-           srcname = os.path.join(src, name)
-           dstname = os.path.join(dst, name)
-           try:
-               if symlinks and os.path.islink(srcname):
-                   linkto = os.readlink(srcname)
-                   os.symlink(linkto, dstname)
-               elif os.path.isdir(srcname):
-                   copytree(srcname, dstname, symlinks)
-               else:
-                   copy2(srcname, dstname)
-               # XXX What about devices, sockets etc.?
-           except OSError as why:
-               errors.append((srcname, dstname, str(why)))
-           # catch the Error from the recursive copytree so that we can
-           # continue with other files
-           except Error as err:
-               errors.extend(err.args[0])
-       try:
-           copystat(src, dst)
-       except OSError as why:
-           # can't copy file access times on Windows
-           if why.winerror is None:
-               errors.extend((src, dst, str(why)))
-       if errors:
-           raise Error(errors)
-
-Another example that uses the :func:`ignore_patterns` helper::
+An example that uses the :func:`ignore_patterns` helper::
 
    from shutil import copytree, ignore_patterns