README.markdown in couchpillow-0.3.7 vs README.markdown in couchpillow-0.3.8

@@ -101,9 +101,20 @@
       rename :username, :nickname
     end
     u = User.new( { :username => 'jdoe' } )
     u.nickname # 'jdoe'
 
+Using `whitelist` to whitelist keys. Also useful to maintain document integrity
+and keeping other fields from being saved. Keep in mind that when loading
+existing documents and if they have keys that are not listed on the whitelist,
+those keys will be dropped upon `save!`.
+
+    class User < CouchPillow::Document
+      whitelist :name
+    end
+    u = User.new( { :age => 10, :name => 'John' } )
+    u.has?(:age) # false
+
 
 ## Design Docs and Views
 
 What about Design Docs and Views? They are outside the scope of CouchPillow.
 However, given a design doc named `my_design_doc` and a View named `by_email`,