Added back-to-top button

Signed-off-by: Jim Martens <github@2martens.de>

_layouts/default.html

@@ -33,6 +33,11 @@
             </div>
         </div>
     </div>
+    <button id="back-to-top"
+       class="btn btn-primary btn-lg"
+       title="Click to return to the start of the page" data-toggle="tooltip" data-placement="left">
+        <span class="fas fa-chevron-square-up"></span>
+    </button>
 </div>
 {% include footer.html %}
 </body>