add Proxy to additional globals tables

website/guide/duktapebuiltins.html

@@ -13,6 +13,7 @@ values.</p>
 </thead>
 <tbody>
 <tr><td class="propname">Duktape</td><td>The Duktape built-in object.  Contains miscellaneous implementation specific stuff.</td></tr>
+<tr><td class="propname">Proxy</td><td>Proxy constructor borrowed from ES6 draft (not part of Ecmascript E5/E5.1).</td></tr>
 <tr><td class="propname">print</td><td>Non-standard, browser-like function for writing to <code>stdout</code>.</td></tr>
 <tr><td class="propname">alert</td><td>Non-standard, browser-like function for writing to <code>stderr</code>.</td></tr>
 </tbody>