<%= nav_bar brand: "BACKEND", responsive: true do %>
    <%= menu_group do %>
      <%= menu_item "notas", backend_notas_path %>
    <% end %>
    <%= menu_group :pull => :right do %>
      <%- if backend_admin_user_signed_in? %>
        <%= menu_item 'Salir', destroy_backend_admin_user_session_path %>
      <% end %>
    <% end %>
<% end %>

<%= nav_bar brand: "BACKEND", responsive: true do %>
    <%= menu_group do %>
      <%= menu_item "Notas", backend_notas_path %>
      <%= menu_item "Usuarios", backend_admin_users_path %>
    <% end %>
    <%= menu_group :pull => :right do %>
      <%- if backend_admin_user_signed_in? %>
        <%= menu_item 'Salir', destroy_backend_admin_user_session_path %>
      <% end %>
    <% end %>
<% end %>

Add admin user to navigation.
Add admin user to navigation.