Collapse main navbar when link is clicked

The main navbar is collapsed automatically on small screens when a tab is
selected.

sao/index.html

@@ -105,6 +105,9 @@ this repository contains the full copyright notices and license terms. -->
                             }
                         }
                     });
+                    jQuery('#main_navbar').on('click', 'a', function() {
+                        jQuery('#main_navbar').collapse('hide');
+                    });
                 });
             }
         </script>