Added documentation for marker draggable

reference.html

@@ -482,6 +482,12 @@ map.addLayer(marker);</code></pre>
 				<td><code>true</code></td>
 				<td>If false, the marker will not emit mouse events and will act as a part of the underlying map.</td>
 			</tr>
+			<tr>
+				<td><code>draggable</code></td>
+				<td>Boolean</td>
+				<td><code>false</code></td>
+				<td>Whether the marker is draggable with mouse/touch or not.</td>
+			</tr>
 		</table>
 		
 		<h3>Methods</h3>