Correct example to use 2D vectors.

docs/api/extras/core/Path.html

@@ -20,9 +20,9 @@
 		<h2>Example</h2>
 
 		<code>
-var v1 = new THREE.Vector3();
-var v2 = new THREE.Vector3(1, 45, 6);
-var v3 = new THREE.Vector3(34, 34, 676);
+var v1 = new THREE.Vector2();
+var v2 = new THREE.Vector2(1, 45);
+var v3 = new THREE.Vector2(34, 34);
 
 var vectors = [v1, v2, v3];