[docs] undocumented classes in library/urllib2.rst

[tomo cocoa]

Hello,

I am Japanese Pythonista and translating Python documents into Japanese.

I found undocumented classes in library/urllib2.rst,
  - HTTPErrorProcessor
  - AbstractHTTPHandler.

The AbstractHTTPHandler may be undocumented
because this class is abstract and used only for implementation of
common methods in its subclasses.

However, I do not realize why the class HTTPErrorProcessor is undocumented.

Regards.

-- 
class Cocoatomo:
    name = 'cocoatomo'
    email_address = 'cocoatomo77 at gmail.com'
    twitter_id = '@cocoatomo'