chore: add description field to atom feed

feed/feed.njk

@@ -23,6 +23,7 @@ eleventyExcludeFromCollections: true
 		<link href="{{ absolutePostUrl }}"/>
 		<updated>{{ post.date | rssDate }}</updated>
 		<id>{{ absolutePostUrl }}</id>
+		<description>{{post.description}}</description>
 		<content type="html">{{ post.templateContent | htmlToAbsoluteUrls(absolutePostUrl) }}</content>
 	</entry>
 	{%- endfor %}