server-tools/base_custom_info/views/webclient_templates.xml

<?xml version="1.0" encoding="utf-8"?>
<odoo>

    <template id="assets_backend"
              name="Backend Assets (used in backend interface)"
              inherit_id="web.assets_backend">
        <xpath expr="." position="inside">
            <script type="text/javascript"
                    src="/base_custom_info/static/src/js/custom_info_renderer.js"/>
            <script type="text/javascript"
                    src="/base_custom_info/static/src/js/custom_info_view.js"/>
            <script type="text/javascript"
                    src="/base_custom_info/static/src/js/relational_fields.js"/>
            <link rel="stylesheet" type="text/scss"
                  href="/base_custom_info/static/src/scss/custom_info.scss"/>
        </xpath>
    </template>

</odoo>