fix the web page archive link to point to sf rather than nabble

svn path=/branches/v0_99_maint/; revision=8375

Author: jdh2358

doc/_templates/indexsidebar.html

@@ -46,7 +46,7 @@ <h3>Need help?</h3>
 <p>Check the <a href="{{ pathto('users/index') }}">user guide</a>,
 the <a href="{{ pathto('faq/index') }}">faq</a>, the <a href="{{
 pathto('api/index') }}">api</a> docs,
-<a href="http://www.nabble.com/matplotlib---users-f2906.html">archives</a>,
+<a href="http://sourceforge.net/mailarchive/forum.php?forum_name=matplotlib-users">archives</a>,
 and join the matplotlib
 mailing <a href="http://sourceforge.net/mail/?group_id=80706">lists</a>.
 The <a href="{{ pathto('search') }}">search</a> tool searches all of