update scene.html

`toJSON` should be a func.

docs/api/en/scenes/Scene.html

@@ -57,7 +57,7 @@
 		Clears scene related data internally cached by [page:WebGLRenderer].
 		</p>
 
-		<h3>[method:Object toJSON]</h3>
+		<h3>[method:Object toJSON]( [param:Object meta] )</h3>
 		<p>
 		meta -- object containing metadata such as textures or images for the scene.<br />
 		Convert the scene to three.js [link:https://github.com/mrdoob/three.js/wiki/JSON-Object-Scene-format-4 JSON Object/Scene format].