added nextcloud link

src/main/resources/templates/dashboard.html

@@ -9,7 +9,7 @@
 	<header>
 		<a th:href="@{/}" class="btn btn-secondary btn-icon-silent" title="aktualisieren"><i class="fas fa-sync"></i></a>
 		<a th:href="@{/business}" class="btn btn-secondary btn-icon-silent" title="Abrechnungen"><i class="far fa-money-bill-alt"></i></a>
-		<span>Das Buchungsportal dess Onkel Werner Freizeiten e.V.</span>
+		<a href="https://www.onkelwernerfreizeiten.de/nextcloud" class="btn btn-secondary btn-icon-silent" title="Nextcloud" target="_blank"><img th:src="@{images/nextcloud.png}" width="20px"/></a>
 	</header>
 	<content>
 	<div class="mainpage">