Store typedef on the helper and use it to show a parameter list

site/components/Parameter.jsx

@@ -0,0 +1,20 @@
+import {object} from 'prop-types';
+import React from 'react';
+import Type from './Type';
+
+function Parameter({param, module, helper}) {
+  return (
+    <li>
+      <code>{param.name}</code> - {param.description} {param.optional && <span>(optional)</span>}<br/>
+      {param.type.names.map(longName => <Type longName={longName} module={module} helper={helper} />)}
+    </li>
+  );
+}
+
+Parameter.propTypes = {
+  param: object.isRequired,
+  module: object.isRequired,
+  helper: object.isRequired
+};
+
+export default Parameter;