add dashboard

app/views/layouts/application.html.erb

@@ -200,6 +200,12 @@
             <%= link_to "Profil", edit_user_registration_path, class: "nav-link" %>
           </li>
 
+          <% if current_user.is_admin? %>
+            <li class="nav-item">
+              <%= link_to "Dashboard", dashboard_path, class: "nav-link" %>
+            </li>
+          <% end %>
+
           <li class="nav-item"><%= link_to "Monatskalender", calendar_month_path(Date.today.year, Date.today.month), class: "nav-link" %></li>
 
           <% if current_user.is_admin? %>