Fix unity "UsingComponents" link

Author: Azzurite

book/component.markdown

@@ -667,7 +667,7 @@ communication paths if you need them.
 ## See Also
 
  *  The [Unity](http://unity3d.com) framework's core [`GameObject`](http://docs.unity3d.com/Documentation/Manual/GameObjects.html) class is designed
-    entirely around [components](http://docs.unity3d.com/Documentation/Manual/UsingComponents40.html).
+    entirely around [components](http://docs.unity3d.com/Manual/UsingComponents.html).
 
  *  The open source [Delta3D](http://www.delta3d.org) engine has a base
     `GameActor` class that implements this pattern with the appropriately named