tweak post.mustache

contrib/templates/default/post.mustache

@@ -19,9 +19,8 @@
   {{#Attachments}}
     <figure>
     <figcaption>
-    <a target="_blank" href="{{Source}}" title="{{Filename}}">{{Filename}}</a>
+    <a target="_blank" href="{{Source}}" title="{{Filename}}"><img src="{{Thumbnail}}" alt="{{Filename}}" /></a>
     </figcaption>
-    <img src="{{Thumbnail}}" alt="{{Filename}}" />
     </figure>
   {{/Attachments}}
 </fieldset>