README.md in knockoutjs-rails-2.2.0.1 vs README.md in knockoutjs-rails-2.2.1

@@ -16,12 +16,17 @@
 
 Add the following directive to your Javascript manifest file (application.js):
 
     //= require knockout
 
+You can optionally add the object mapping plugin for Knockout (also
+application.js):
+
+    //= require knockout.mapping
+
 ## Versioning
 
-knockoutjs-rails 2.2.0 == Knockout.js 2.2.0
+knockoutjs-rails 2.2.1 == Knockout.js 2.2.1
 
 Every attempt is made to mirror the currently shipping Knockout.js version number wherever possible.
 The major and minor version numbers will always represent the Knockout.js version, but the patch level
 may differ should a fix to gem need to be pushed before Knockout.js ships an update to the library.