Allow render rules to be customized using render presets

Signed-off-by: Danila Fedorin <danila.fedorin@gmail.com>

layouts/shortcodes/bergamot_widget.html

@@ -1,6 +1,6 @@
 <div id="{{ .Get "id" }}"></div>
 <script>
     window.addEventListener('load', function() {
-        window.Bergamot.run(null, '{{ .Get "id" }}', '{{ .Get "prompt" }}', '{{ .Inner }}', renderRules, '{{ .Get "query" }}');
+        window.Bergamot.run(null, '{{ .Get "id" }}', '{{ .Get "prompt" }}', '{{ .Inner }}', '{{ default "default" (.Get "rendering") }}', '{{ .Get "query" }}');
     });
 </script>