rm global header

doc/en/_templates/layout.html

@@ -1,19 +1,5 @@
 {% extends "!layout.html" %}
 {% 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#/">
-        contribute to
-    </a>
-    or 
-    <a href="announce/sprint2016.html">
-        join
-    </a>
-    our upcoming sprint in June 2016!
-
-  </h4>
-</div>
   {{super()}}
 {% endblock %}
 {% block footer %}