Updating README for :layout => true.

README.rdoc

@@ -189,6 +189,13 @@ method:
     haml :index
   end
 
+Some times you'll want to render a specific template with or without a
+layout based on whether the request is Ajax or not:
+
+  get '/' do
+    haml :index, :layout => !request.xhr?
+  end
+
 == Helpers
 
 The top-level <tt>helpers</tt> method