some layout refinements

doc/en/_templates/layout.html

@@ -2,9 +2,16 @@
 {% block header %}
 <div align="center" xmlns="http://www.w3.org/1999/html" style="background-color: lightgreen;  padding: .5em">
   <h4>
+      Want to help improve pytest?  Please 
     <a href="https://www.indiegogo.com/projects/python-testing-sprint-mid-2016#/">
-      Support the future of py.test development: join or fund the next sprint in June in Germany
+        contribute to
     </a>
+    or 
+    <a href="announce/sprint2016.html">
+        join
+    </a>
+    our sprint June in 2016!
+
   </h4>
 </div>
   {{super()}}