[doxygen] adapt modules.txt to new groups and add link to logo

doc/doxygen/header.html

@@ -26,7 +26,7 @@ $extrastylesheet
  <tbody>
  <tr style="height: 56px;">
   <!--BEGIN PROJECT_LOGO-->
-  <td id="projectlogo"><img alt="Logo" src="$relpath^$projectlogo"/></td>
+  <td id="projectlogo"> <a href="https://dumux.org"> <img alt="Logo" src="$relpath^$projectlogo"/></a></td>
   <!--END PROJECT_LOGO-->
   <!--BEGIN PROJECT_NAME-->
   <td id="projectalign" style="padding-left: 0.5em;">