<li class="thredded--user-navigation--item thredded--user-navigation--private-topics">
  <%= link_to private_topics_path do %>
    <%= inline_svg 'thredded/private-messages.svg', class: 'thredded--icon' %>
    <%= t('thredded.nav.private_topics') %>
    <% if unread_private_topics_count > 0 -%>
          <span class="thredded--user-navigation--private-topics--unread">
            <%= unread_private_topics_count %>
          </span>
    <% end -%>
  <% end -%>
</li>

<li class="thredded--user-navigation--item thredded--user-navigation--private-topics">
  <%= link_to private_topics_path, rel: 'nofollow' do %>
    <%= inline_svg 'thredded/private-messages.svg', class: 'thredded--icon' %>
    <%= t('thredded.nav.private_topics') %>
    <% if unread_private_topics_count > 0 -%>
          <span class="thredded--user-navigation--private-topics--unread">
            <%= unread_private_topics_count %>
          </span>
    <% end -%>
  <% end -%>
</li>

Add `rel="nofollow"` to private topics link
[JRO] Add `rel="nofollow"` to private topics link

We don't want search engines trying to follow this link.

Closes issue #257
