Added NNTP info to Boost Testing mailing list description

[SVN r25698]

more/mailing_lists.htm

@@ -266,6 +266,12 @@
         for a particular library, should be posted to main development
         list.</p>
 
+        <a
+        href="news://news.gmane.org/gmane.comp.lib.boost.documentation">NNTP
+        access</a> and <a
+        href="http://news.gmane.org/gmane.comp.lib.boost.testing">Searchable
+        Archives</a> are available on <a href="http://www.gmane.org">GMane</a>.
+