prints a message then the `--bootstrap` option is used.

closes #376.

lib/generators/simple_form/install_generator.rb

@@ -14,6 +14,12 @@ module SimpleForm
         engine = options[:template_engine]
         copy_file "_form.html.#{engine}", "lib/templates/#{engine}/scaffold/_form.html.#{engine}"
       end
+
+      def show_readme
+        if behavior == :invoke && options.bootstrap?
+          readme "README"
+        end
+      end
     end
   end
 end

lib/generators/simple_form/templates/README

@@ -0,0 +1,12 @@
+===============================================================================
+
+  Be sure to have a copy of the Bootstrap stylesheet available on your app,
+  you can get in on http://twitter.github.com/bootstrap.
+
+  Inside your views, use the 'simple_form_for' with one of the Bootstrap form
+  classes, '.form-horizontal', '.form-inline', '.form-search' or
+  '.form-vertical', as the following:
+
+    = simple_form_for(@user, :html => {:class => 'form-horizontal' }) do |form|
+
+===============================================================================