app/views/cats/build/add_bio.html.erb
<h2>Cuéntanos más</h2>
<%= form_for(@cat, :url => wizard_path, :method => :put) do |f| %>
<div class="field">
<%= f.label :bio %><br>
<%= f.text_area :bio, class: 'form-control' %>
</div>
<br>
<%= f.submit 'Siguiente', :class => 'btn btn-primary' %>
<% end %>