update clone Method to Face4 documentation

docs/api/core/Face4.html

@@ -92,7 +92,14 @@
 		Face centroid.
 		</div>
 
+		<h2>Methods</h2>
 
+		<h3>.clone()</h3>
+		<div>
+		Creates a new clone of the Face4 object.
+		</div>
+		
+		
 		<h2>Source</h2>
 
 		[link:https://github.com/mrdoob/three.js/blob/master/src/[path].js src/[path].js]