Add Bulma Dashboard to list of extensions (#2277)

* Add extension and image

* Add new extension image

docs/extensions.html

@@ -123,6 +123,9 @@ extensions:
   slug: bulma-toast
   width: 208
   height: 173
+- name: bulma-dashboard
+  url: https://github.com/lucperkins/bulma-dashboard
+  slug: bulma-dashboard
 ---
 
 {% for extension in page.extensions %}