Multiple small template improvements

templates/index.html

@@ -33,5 +33,7 @@
 <section>
 	<h2>Did you know?</h2>
 	<p>If you share this site and the Link gets a preview. The IP-Address after the dash is the one of the machine that generated that preview.</p>
+	<p>This service exports a <a href="{{ extra.base_url }}/dns_resolver">list of dns resolvers it supports</a>, with configuration.</p>
+	<p>Every query that can output html can also output json or plain text using the <code>?format=json</code> or <code>?format=text</code> url parameters?</p>
 </section>
 {% endblock %}