[Docs] Reference periodic tasks docs

docs/admin/10_rss_feed_widget.rst

@@ -11,11 +11,11 @@ In addition, the news source is linked on the dashboard.
 * **Base URL**: The home or base URL of the news provider
 * **Text only**: With this being enabled, no images will be shown.
 
-.. warning::
+.. note::
 
     The RSS widget provides a task to pull data. The task ``get_feeds`` updates all active RSS feeds inside AlekSIS. 
-    We recommend to run the task every 5 to 10 minutes. This can be done by a periodic task. Without running  this task, 
-    the dashboard widget will be just empty.
+    We recommend to run the task every 5 to 10 minutes. The task is automatically scheduled every 10 minutes;
+    this can be changed as described in :ref:`core-periodic-tasks`.
 
 .. image:: ../_static/create_rss_widget.png
   :width: 100%