Add template for wiki summary pages

templates/wikilink.html

+{% extends "page.html" %}
+
+{% block main %}
+  {% include "pages/heading.html" %}
+  <div class="my-4">
+    <div class="content container">
+      {% if page.content %}
+        {{ page.content | safe }}
+	<p>In unserem Wiki gibt es <a href="{{ page.extra.wiki_link }}">detaillierte Informationen</a> zu diesem Thema.</p>
+      {% else %}
+        {% include "baustelle.html" %}
+      {% endif %}
+    </div>
+  </div>
+{% endblock %}