Add footer social buttons.

docs/_includes/footer.html

@@ -2,6 +2,7 @@
 ================================================== -->
 <footer class="bs-docs-footer" role="contentinfo">
   <div class="container">
+    {% include social-buttons.html %}
 
     <p>Designed and built with all the love in the world by <a href="https://github.com/wenzhixin" target="_blank">@wenzhixin</a>.</p>
     <p>Maintained by <a href="https://github.com/wenzhixin" target="_blank">@wenzhixin</a> with the help of <a href="https://github.com/wenzhixin/bootstrap-table/graphs/contributors" target="_blank">our contributors</a>.</p>