Add proper license for picture

Author: tkuhn

assets/img/incubator2daniel.jpg

@@ -152,7 +152,9 @@ <h3 id="incubator1">#1: FAIR Vocabularies for Chemical Risk Assessment</h3 id="i
 <section>
 
 <div class="portrait" id="incubator2daniel">
-<img src="assets/img/incubator2daniel.jpg" alt="Daniel Mietchen" style="float: right; margin: 2em;"/>
+<a title="Ralf Rebmann, CC BY-SA 4.0 &lt;https://creativecommons.org/licenses/by-sa/4.0&gt;, via Wikimedia Commons" href="https://commons.wikimedia.org/wiki/File:Daniel_Mietchen.jpg">
+<img alt="Daniel Mietchen" src="https://upload.wikimedia.org/wikipedia/commons/thumb/b/b7/Daniel_Mietchen.jpg/512px-Daniel_Mietchen.jpg?20171011081717" style="float: right; margin: 2em;">
+</a>
 </div>
 
 <h3 id="incubator2">#2: nanopublication-Enhanced Open Science Communication (nEOSC)</h3>