terraform/website/source/layouts/dns.erb

<% wrap_layout :inner do %>
  <% content_for :sidebar do %>
    <div class="docs-sidebar hidden-print affix-top" role="complementary">
      <ul class="nav docs-sidenav">
        <li<%= sidebar_current("docs-home") %>>
        <a href="/docs/providers/index.html">All Providers</a>
                </li>

        <li<%= sidebar_current("docs-dns-index") %>>
        <a href="/docs/providers/dns/index.html">DNS Provider</a>
                </li>

                <li<%= sidebar_current("docs-aws-datasource") %>>
                <a href="#">Data Sources</a>
                    <ul class="nav nav-visible">

                        <li<%= sidebar_current("docs-dns-datasource-a-record-set") %>>
                            <a href="/docs/providers/dns/d/dns_a_record_set.html">dns_a_record_set</a>
                        </li>
                        <li<%= sidebar_current("docs-dns-datasource-cname-record-set") %>>
                            <a href="/docs/providers/dns/d/dns_cname_record_set.html">dns_cname_record_set</a>
                        </li>
                        <li<%= sidebar_current("docs-dns-datasource-txt-record-set") %>>
                            <a href="/docs/providers/dns/d/dns_txt_record_set.html">dns_txt_record_set</a>
                        </li>
                    </ul>
                </li>

        <li<%= sidebar_current("docs-dns") %>>
        <a href="#">Resources</a>
                <ul class="nav nav-visible">
                    <li<%= sidebar_current("docs-dns-a-record-set") %>>
          <a href="/docs/providers/dns/r/dns_a_record_set.html">dns_a_record_set</a>
                    </li>
                    <li<%= sidebar_current("docs-dns-aaaa-record-set") %>>
          <a href="/docs/providers/dns/r/dns_aaaa_record_set.html">dns_aaaa_record_set</a>
                    </li>
                    <li<%= sidebar_current("docs-dns-cname-record") %>>
          <a href="/docs/providers/dns/r/dns_cname_record.html">dns_cname_record</a>
                    </li>
                    <li<%= sidebar_current("docs-dns-ptr-record") %>>
          <a href="/docs/providers/dns/r/dns_ptr_record.html">dns_ptr_record</a>
                    </li>
                </ul>
        </li>
      </ul>
    </div>
  <% end %>

  <%= yield %>
<% end %>