fix image path

themes/c3mkdocs/main.html

@@ -11,6 +11,6 @@ the blocks defined in base.html and its included child templates.
 
 {%- block footer %}
 <hr>
-<p>Sponsored by <a href="https://www.hetzner.de"><img src="img/Hetzner_Logo.png" alt="hetzner online" width="50px" /></a>. Documentation built with <a href="https://www.mkdocs.org/">MkDocs</a>. <a href="https://events.ccc.de/impressum/">Impressum</a></p>
+<p>Sponsored by <a href="https://www.hetzner.de"><img src="/img/Hetzner_Logo.png" alt="hetzner online" width="50px" /></a>. Documentation built with <a href="https://www.mkdocs.org/">MkDocs</a>. <a href="https://events.ccc.de/impressum/">Impressum</a></p>
 
 {%- endblock %}