add github icon and change the lock icon

_includes/themes/cgal/default.html

@@ -122,14 +122,17 @@ <h1>{{ page.title }} {% if page.tagline %} <small>{{ page.tagline }}</small>{% e
         <div class="col-md-12">
           <div class="footer-copyright">
             <div style="float: left;">
+              <a href="https://github.com/cgal/cgal" alt="The CGAL Project's github">
+                <i class="bi bi-github btn-dark-orange"></i>
+              </a>
               <a href="https://twitter.com/TheCGALProject" alt="The CGAL Project's Twitter">
                 <img src="{{ BASE_PATH }}/images/icons/twitter.svg" class="center-block btn-dark-orange" alt="Twitter" height="18"></img>
               </a>
             </div>
             &copy; 1995-{{site.time | date: "%Y"}} The CGAL Project. All rights reserved.
             <div style="float: right;">
               <a href="https://cgal.geometryfactory.com/CGAL/Members/wiki/Main_Page" alt="Password protected access to the Developer Wiki">
-                <i class="bi bi-lock-fill fs-5"></i>
+                <i class="bi bi-file-lock fs-5"></i>
               </a>
             </div>
           </div>