Small update needed for Rails Guide: Getting Started with Rails

I just finished Section 6, Creating a Resource (posts). I viewed my first post at http://localhost:3000/posts/1 to try out the adding comments functionality. The page displayed with the correct content, but with this message printed immediately after the Add a Comment heading:

DEPRECATION WARNING: f.error_messages was removed from Rails and is now available as a plugin. Please install it with `rails plugin install git://github.com/rails/dynamic_form.git`. (called from block in _app_views_posts_show_html_erb___58482907_24223368__383082239 at C:/ Users/carol/carol/Programming/rails/rails_projects/blog/app/views/ posts/show.html.erb:29)

The corresponding code for the comments section in app/views/posts/ show.html.erb is:

<%= form_for([@post, @post.comments.build]) do |f| %>     <%= f.error_messages %>

    <div class="field">       <%= f.label :commenter %><br />       <%= f.text_field :commenter %>     </div>

    <div class="field">       <%= f.label :body %><br />       <%= f.text_area :body %>     </div>

    <div class="actions">       <%= f.submit %>     </div> <% end %>

I have done some basic study of Rails 2 during the past few months (but am still new to programming), so this seems like an item that remains to be changed in updating the tutorial from Rails 2 to Rails 3.

As I said, comments can still be created, but the message might confuse or alarm someone new to programming.

Thank you,

Carol