If I understand correctly, the lines:

    <% content_for :head do -%>
    <%= auto_discovery_link_tag :atom, :action => 'rss', :language => params[:language] %>
    <% end -%>

needs to be wrapped in `<% unless params[:friends] or params[:nearby] -%>`, right? 

What exactly is the `auto_discovery_link_tag` doing here?