Remove incorrect GLTFExporter documentation

docs/examples/exporters/GLTFExporter.html

@@ -25,7 +25,7 @@
 
 		<code>
 		// Instantiate a exporter
-		var exporter = new THREE.GLTFExporter( defaultOptions );
+		var exporter = new THREE.GLTFExporter();
 
 		// Parse the input and generate the glTF output
 		exporter.parse( scene, function ( gltf ) {