Update feed.xml

Author: Daniele-rolli

feed.xml

@@ -2,7 +2,10 @@
 layout: none
 ---
 <?xml version="1.0" encoding="UTF-8" ?>
-<rss version="2.0" xmlns:media="http://search.yahoo.com/mrss/" xmlns:content="http://purl.org/rss/1.0/modules/content/">
+<rss version="2.0"
+  xmlns:media="http://search.yahoo.com/mrss/"
+  xmlns:content="http://purl.org/rss/1.0/modules/content/"
+  xmlns:atom="http://www.w3.org/2005/Atom">
   <channel>
     <title>{{ site.title }}</title>
     <link>{{ site.url }}</link>