mastodon link in the required unstyled form (hidden)

Author: gluap

content/_index.de.html

@@ -11,6 +11,9 @@
 ---
 
 {{< blocks/cover title="OpenBikeSensor" image_anchor="top" height="400" >}}
+<!-- mastodon needs exactly this a href for verification. Because it's hard to style let's put it here and hide it. Clickable link below -->
+<div style="display:none"><a href="https://verkehrswende.social/@OpenBikeSensor" rel="me">mastodon</a></div>
+
 <div class="mx-auto">
 
 	<h2 class="display-4 mb-3">Überholabstandsmessung für Radfahrende</h2>