Link to blog post

as suggested by @mgedmin on zopefoundation/zope.file#1

CHANGES.rst

@@ -100,7 +100,9 @@ CHANGES
     to ::
 
         >>> from zope.testbrowser.wsgi import Browser
-
+        
+    Maybe the blog post `Getting rid of zope.app.testing`_ could help you adapting to this new version, too.
+
 - Remove modules:
 
   - ``zope.testbrowser.connection``
@@ -143,6 +145,9 @@ CHANGES
   (https://github.com/zopefoundation/zope.testbrowser/pull/3).
 
 
+.. `Getting rid of zope.app.testing`_ : https://icemac15.wordpress.com/2010/07/10/appswordpressicemac20100710get-rid-of-zope-app-testing-dependency/
+
+
 4.0.3 (2013-09-04)
 ------------------