add v4 message

Author: filipesilva

public/docs/ts/latest/cookbook/third-party-lib.jade

@@ -13,6 +13,10 @@ include ../_util-fns
 
   This cookbook shows how to publish a third party library in a way that makes it possible to take advantage of techniques like Ahead of Time Compilation (AOT) and Tree Shaking.
 
+.alert.is-important
+  :marked
+    The setup shown in this cookbook is only for Angular version 4 (and up) libraries.
+
 <a id="toc"></a>
 :marked
   ## Table of contents