Use element.href if data-url is not present

Author: humitos

hoverxref/_static/js/hoverxref.js_t

@@ -174,7 +174,9 @@ $(document).ready(function() {
     {% endif %}
 
     function showModal(element) {
-        var url = element.data('url');
+        // TODO: we are failing on some elements to set the URL from the
+        // backend, but we can use `href` instead.
+        var url = element.data('url') || element.href;
         var url = getEmbedURL(url);
         $.get(url, function(data) {
             var content = $('<div></div>');