add trailing slash to posts links

lib/layouts/index_layout.ex

@@ -14,7 +14,7 @@ defmodule MonoTab.IndexLayout do
       <ul>
         <%= for post <- @posts do %>
           <li>
-            <h2><a href={post.permalink}>{post.title}</a></h2>
+            <h2><a href={"#{post.permalink}/"}>{post.title}</a></h2>
             <%= if post[:date] do %>
               <time datetime={post[:date]}>{format_date(post[:date])}</time>
             <% end %>