add note about cpXXXan to FAQ

src/misc/cpan-faq.html

@@ -369,9 +369,12 @@ <h3>
     storage space).
 </p>
 <ul>
+    <li>
+        <a href="http://cpxxxan.barnyard.co.uk/">http://cpxxxan.barnyard.co.uk/</a> - for versions of modules that are known to pass their tests on particular versions of perl or particular platforms, such as perl 5.8.8 on Irix
+    </li>
     <li>
         <a href="http://backpan.perl.org/">http://backpan.perl.org/</a> - for
-        old versions of modules
+        an archive of all the old versions of all modules
     </li>
 </ul>
 <hr>