add github card

Author: MuellerSeb

_posts/2019-01-05-about.md

@@ -15,3 +15,8 @@ You can contact us via <info@geostat-framework.org>.
 <img src="/img/UFZ_LOGO.jpg" alt="UFZ" width="20%">
 <img src="/img/dbu.png" alt="DBU" width="20%">
 </p>
+
+<p align="center">
+<div class="github-card" data-github="MuellerSeb" data-width="400" data-height="" data-theme="default"></div>
+<script src="//cdn.jsdelivr.net/github-cards/latest/widget.js"></script>
+</p>