README.md in govuk_elements_rails-0.1.1 vs README.md in govuk_elements_rails-0.2.1

@@ -41,9 +41,16 @@
     // from govuk_elements gem
     //= require details.polyfill
     //= require bind
     //= require selection-buttons
 
+## Usage of GovukElementsFormBuilder
+
+To replace the default form builder with a version that generates GOV.UK Elements classed markup, set the following in
+config/application.rb:
+
+    config.use_govuk_elements_form_builder = true
+
 ## Alternate ways to reuse GOV.UK Elements
 
 There are other alternate ways to include GOV.UK Elements files in a Rails
 project, for example via `Bower`. Feel free to use an alternate approach if it
 is more appropriate for your team.