app/views/spree/admin/shared/sub_menu/_documents_sub_menu.html.erb
<ul id="sidebar-documents" class="border-top bg-white collapse nav nav-pills nav-stacked" data-hook="admin_documents_sub_tabs">
<%= tab :invoices, url: spree.admin_bookkeeping_documents_path(q: { template_eq: 'invoice' }) %>
<%= tab :packaging_slips, url: spree.admin_bookkeeping_documents_path(q: { template_eq: 'packaging_slip' }) %>
</ul>