Update nntplib examples to use a public news server.

The example still doesn't work as-is under py3k, due to incomplete
or buggy porting of the nntplib module.

Doc/library/nntplib.rst

@@ -18,35 +18,35 @@ Protocol), see Internet :rfc:`977`.
 Here are two small examples of how it can be used.  To list some statistics
 about a newsgroup and print the subjects of the last 10 articles::
 
-   >>> s = NNTP('news.cwi.nl')
-   >>> resp, count, first, last, name = s.group('comp.lang.python')
+   >>> s = NNTP('news.gmane.org')
+   >>> resp, count, first, last, name = s.group('gmane.comp.python.committers')
    >>> print('Group', name, 'has', count, 'articles, range', first, 'to', last)
-   Group comp.lang.python has 59 articles, range 3742 to 3803
+   Group gmane.comp.python.committers has 1071 articles, range 1 to 1071
    >>> resp, subs = s.xhdr('subject', first + '-' + last)
    >>> for id, sub in subs[-10:]: print(id, sub)
    ...
-   3792 Re: Removing elements from a list while iterating...
-   3793 Re: Who likes Info files?
-   3794 Emacs and doc strings
-   3795 a few questions about the Mac implementation
-   3796 Re: executable python scripts
-   3797 Re: executable python scripts
-   3798 Re: a few questions about the Mac implementation
-   3799 Re: PROPOSAL: A Generic Python Object Interface for Python C Modules
-   3802 Re: executable python scripts
-   3803 Re: \POSIX{} wait and SIGCHLD
+   1062 Re: Mercurial Status?
+   1063 Re: [python-committers]  (Windows) buildbots on 3.x
+   1064 Re: Mercurial Status?
+   1065 Re: Mercurial Status?
+   1066 Python 2.6.6 status
+   1067 Commit Privileges for Ask Solem
+   1068 Re: Commit Privileges for Ask Solem
+   1069 Re: Commit Privileges for Ask Solem
+   1070 Re: Commit Privileges for Ask Solem
+   1071 2.6.6 rc 2
    >>> s.quit()
-   '205 news.cwi.nl closing connection.  Goodbye.'
+   '205 Bye!'
 
 To post an article from a file (this assumes that the article has valid
-headers)::
+headers, and that you have right to post on the particular newsgroup)::
 
-   >>> s = NNTP('news.cwi.nl')
+   >>> s = NNTP('news.gmane.org')
    >>> f = open('/tmp/article')
    >>> s.post(f)
    '240 Article posted successfully.'
    >>> s.quit()
-   '205 news.cwi.nl closing connection.  Goodbye.'
+   '205 Bye!'
 
 The module itself defines the following items: