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" version="7.0">
                <field name="diff" widget="html" class="overflow-x: scroll" />
                <footer>
                    <button string="Close" class="oe_link" special="cancel" />
                </footer>
            </form>
        </field>
    </record>

    <!-- Create Index Action Window  -->
    <act_window
            id="action_view_wiki_show_diff_values"
            name="Difference"
            res_model="wizard.document.page.history.show_diff"
            binding_model="document.page.history"
            view_mode="form"
            target="new"/>

</odoo>