show all users on ranking board; be able to merge users

templates/admin/user/index.html.tera

@@ -4,6 +4,9 @@
     <div class="max-w-screen-lg w-full">
         <h1 class="h1">Users</h1>
         {% if allowed_to_edit %}
+            <div class="mt-5 flex gap-3">
+                <a href="/admin/user/merge" class="btn btn-dark">Benutzer zusammenführen</a>
+            </div>
             <details class="mt-5 bg-gray-200 dark:bg-primary-600 p-3 rounded-md">
                 <summary class="px-3 cursor-pointer text-md font-bold text-primary-950 dark:text-white">
                     Neue Person hinzufügen