[docs] Add bootstrap-collapse plugin, fixing collapsing navbar.

docs/template.html

@@ -143,10 +143,11 @@ margin-top: 5px;
     <script src="{{ base_url }}/js/jquery.js"></script>
     <script src="{{ base_url }}/js/bootstrap-dropdown.js"></script>
     <script src="{{ base_url }}/js/bootstrap-scrollspy.js"></script>
+    <script src="{{ base_url }}/js/bootstrap-collapse.js"></script>
     <script>
-    //$('.side-nav').scrollspy()
-    var shiftWindow = function() { scrollBy(0, -50) };
-    if (location.hash) shiftWindow();
-    window.addEventListener("hashchange", shiftWindow);
+      //$('.side-nav').scrollspy()
+      var shiftWindow = function() { scrollBy(0, -50) };
+      if (location.hash) shiftWindow();
+      window.addEventListener("hashchange", shiftWindow);
     </script>
 </body></html>
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