Update contact link to ESMValTool Team

Author: LisaBock

_includes/lesson_footer.html

@@ -77,7 +77,7 @@
       <th>Acknowledgements</th>
     </tr>
     <tr>
-      <td><p style="font-size:95%;"><a href="javascript:mail('birgit.hassler','dlr.de')">Birgit Hassler (Project Co-PI)</a></p></td>
+      <td><p style="font-size:95%;"><a href="javascript:mail('esmvaltool-contact','dlr.de')">ESMValTool Team</a></p></td>
       <td><p style="font-size:95%;"><a href="https://esmvaltool.org/legal_notice/">Legal Notice</a></p></td>
 <!--    <td><p style="font-size:95%;"><a href="https://esmvaltool.org/privacy/">Privacy Notice</a></p></td>-->
       <td><p style="font-size:95%;"><a href="https://esmvaltool.org/terms_of_use/">Terms of use</a></p></td>