New Haskell implementation hjsonschema.

Also make it easy to change the list of implementations.

Author: alexanderkjeldaas

content/implementations.html

@@ -4,6 +4,9 @@
 
 	<p>Implementations below are classified based on their functionality.  When known, the
 	license of the project is also mentioned.</p>
+	
+	<p>If you have updates to this list, Look at the <a href="https://github.com/json-schema/json-schema">GitHub repo</a>
+	under the gh-pages branch</p>
 </div>
 
 <div class="show-hide" data-target="validator-list"></div>
@@ -69,6 +72,7 @@ <h3>C</h3>
 	<h3>Haskell</h3>
 	<ul>
 		<li><a id="link-impl-aeson-schema" href="https://github.com/timjb/aeson-schema">aeson-schema</a> (MIT)</li>
+		<li><a id="link-impl-hjsonschema" href="https://github.com/seagreen/hjsonschema">hjsonschema</a> - <em>supports version 4</em> (MIT)</li>
 	</ul>
 
 	<h3>Erlang</h3>