Add aside with link to feeds

src/blog/index.html

@@ -9,6 +9,12 @@ pagination:
 <main class="wrapper-md stack-lg">
     <h1>Blog posts</h1>
 
+    <aside class="text-center">
+        <p>
+            Subscribe via <a href="/rss.xml">RSS</a>, <a href="/atom.xml">Atom</a>, or <a href="/feed.json">JSON</a>.
+        </p>
+    </aside>
+
     <ol class="stack-xl" role='list'>
         {% for item in pagination.items %}
         <li class="stack-xs">