knowledge/document_page/wizard/document_page_show_diff.xml

<?xml version="1.0" encoding="utf-8" ?>
<odoo>
    <!-- Create Index Form view  -->
    <record id="view_wiki_show_diff" model="ir.ui.view">
        <field name="name">Show Difference</field>
        <field name="model">wizard.document.page.history.show_diff</field>
        <field name="arch" type="xml">
            <form string="Difference">
                <field name="diff" widget="html" class="overflow-x: scroll" />
                <footer>
                    <button string="Close" class="oe_link" special="cancel" />
                </footer>
            </form>
        </field>
    </record>

    <record model="ir.actions.act_window" id="action_view_wiki_show_diff_values">
        <field name="name">Difference</field>
        <field name="res_model">wizard.document.page.history.show_diff</field>
        <field name="view_mode">form</field>
        <field name="target">new</field>
        <field
            name="binding_model_id"
            ref="document_page.model_document_page_history"
        />
    </record>
</odoo>