Fix footer about us link

Author: jeroendesloovere

_includes/footer.html

@@ -2,7 +2,7 @@
   <div class="row">
     <ul class="nav">
       <li class="nav-item"><span class="nav-link">&copy; 2018 DockerWest</span></li>
-      <li class="nav-item"><a class="nav-link" href="{{ site.repo }}/about">About us</a></li>
+      <li class="nav-item"><a class="nav-link" href="{{ site.baseurl }}/about">About us</a></li>
       <li class="nav-item"><a class="nav-link" href="https://hub.docker.com/u/dockerwest/" target="_blank">DockerWest on Docker Hub</a></li>
       <li class="nav-item"><a class="nav-link" href="https://github.com/dockerwest" target="_blank">DockerWest on Github</a></li>
     </ul>