Add RSS template file

src/rss.njk

@@ -0,0 +1,28 @@
+---
+permalink: '/feed.xml'
+---
+<?xml version="1.0" encoding="utf-8"?>
+<feed xmlns="http://www.w3.org/2005/Atom">
+  <title>{% if title %}{{ title }}{% else %}{{ meta.siteName }}{% endif %}</title>
+	<subtitle>{% if summary %}{{ summary }}{% else %}{{ meta.siteDescription}}{% endif %}</subtitle>
+	<link href="{{ meta.url }}{{ permalink }}" rel="self"/>
+	<link href="{{ meta.url }}/"/>
+	<updated>{{ collections.posts | rssLastUpdatedDate }}</updated>
+	<id>{{ meta.url }}</id>
+	<author>
+    <name>{{ meta.author }}</name>
+    <email>{{ meta.authorEmail }}</email>
+	</author>
+	{% for post in collections.posts %}
+    {% set absolutePostUrl %}{{ meta.url }}{{ post.url | url }}{% endset %}
+    <entry>
+      <title>{{ post.data.title }}</title>
+      <link href="{{ absolutePostUrl }}"/>
+      <updated>{{ post.date | rssDate }}</updated>
+      <id>{{ absolutePostUrl }}</id>
+      <content type="html"><![CDATA[
+        {{ post.templateContent | safe }}
+      ]]></content>
+    </entry>
+	{% endfor %}
+</feed>