Update contact info (#4348)

Author: axel-lauer

doc/sphinx/source/_templates/layout.html

@@ -59,8 +59,7 @@
     <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><br>
-        <a href="javascript:mail('axel.lauer','dlr.de')">Axel Lauer (Core Developer)</a><br></p></td>
+     <td><p style="font-size:95%;"><a href="javascript:mail('birgit.hassler','dlr.de')">Birgit Hassler (Project Co-PI)</a><br></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>