update setLength documentation to reflect code

docs/api/extras/helpers/ArrowHelper.html

@@ -70,9 +70,11 @@
 		Sets the color of the arrowHelper.
 		</div>
 
-		<h3>.setLength([page:Number length])</h3>
+		<h3>.setLength([page:Number length], [page:Number headLength], [page:Number headWidth])</h3>
 		<div>
-		length -- The desired length
+		length -- The desired length<br />
+		headLength -- The length of the head of the arrow<br />
+		headWidth -- The length of the width of the arrow		
 		</div>
 		<div>
 		Sets the length of the arrowhelper.