app/views/categories/show.html.erb
<% @page_title = @category.display_name %>
<h1><%= @category.display_name %></h1>
<%= link_to 'Back', :back %>
<div class='attached_records'>
<h2>Companies</h2>
<% @companies.each do |company| %>
<li><%= link_to company.name, company %></li>
<% end %>
</div>