[docs] RSS: Pass title through xml_escape

feed.xml

@@ -10,7 +10,7 @@ layout: none
 		<atom:link href="{{ site.url }}{{ site.baseurl }}/feed.xml" rel="self" type="application/rss+xml" />
 		{% for post in site.posts limit:10 %}
 			<item>
-				<title>{{ post.title }}</title>
+				<title>{{ post.title | xml_escape }}</title>
 				<description>{{ post.content | xml_escape }}</description>
 				<pubDate>{{ post.date | date_to_xmlschema }}</pubDate>
 				<link>{{ site.url }}{{ site.baseurl }}{{ post.url }}</link>