discourse/app/views/categories/index.html.erb

<div class='category-list' itemscope itemtype='http://schema.org/ItemList'>
  <meta itemprop='itemListOrder' content='http://schema.org/ItemListOrderDescending'>
  <% @list.categories.each do |c| %>
    <div class='category' itemprop='itemListElement' itemscope itemtype='http://schema.org/ListItem'>
      <meta itemprop='url' content='<%= c.url %>'>
      <h2><a href='<%= c.url %>' itemprop='item'>
        <span itemprop='name'><%= c.name %></span>
      </a></h2>
      <span itemprop='description'><%= c.description %></span>
      <div class='topic-list' itemscope itemtype='http://schema.org/ItemList'>
        <%- if c.displayable_topics.present? %>
          <% c.displayable_topics.each do |t| %>
            <div itemprop='itemListElement' itemscope itemtype='http://schema.org/ListItem'>
              <meta itemprop='url' content='<%= t.url %>'>
              <a href='<%= t.relative_url %>' itemprop='item'>
                <span itemprop='name'><%= t.title %></span>
              </a> <span title='<%= t 'posts' %>'>(<%= t.posts_count %>)</span>
            </div>
          <% end %>
        <%- end %>
      </div>
    </div>
  <% end %>
</div>

<% content_for :title do %><%= @title %><% end %>