docs/news.html: add 2013.08 announcement mail link

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

docs/news.html

@@ -10,7 +10,7 @@
     <p>The stable 2013.08 release is out - Thanks to everyone
     contributing and testing the release candidates. See the
     <a href="http://git.buildroot.net/buildroot/plain/CHANGES?id=2013.08">CHANGES</a>
-    file for more details
+    file for more details, read the <a href="http://lists.busybox.net/pipermail/buildroot/2013-August/077224.html">announcement</a>
     and go to the <a href="/downloads/">downloads page</a> to pick up the
     <a href="/downloads/buildroot-2013.08.tar.bz2">2013.08 release</a>.</p>