Fix function name: open -> urlopen.

Doc/howto/urllib2.rst

@@ -140,7 +140,7 @@ This is done as follows::
     name=Somebody+Here&language=Python&location=Northampton
     >>> url = 'http://www.example.com/example.cgi'
     >>> full_url = url + '?' + url_values
-    >>> data = urllib.request.open(full_url)
+    >>> data = urllib.request.urlopen(full_url)
 
 Notice that the full URL is created by adding a ``?`` to the URL, followed by
 the encoded values.