knowledge/document_knowledge/views/knowledge.xml

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

    <record id="knowledge_action_documents" model="ir.actions.act_window">
        <field name="name">Documents</field>
        <field name="res_model">ir.attachment</field>
        <field name="view_mode">kanban,tree,form</field>
        <field name="context">{'search_default_user_documents': True}</field>
    </record>


    <record id="ir_attachment_view_user_documents" model="ir.ui.view">
        <field name="name">Documents search view: additional filters</field>
        <field name="model">ir.attachment</field>
        <field name="inherit_id" ref="base.view_attachment_search"/>
        <field name="arch" type="xml">
            <search>
                <field name="res_model"/>
                <field name="index_content"/>
                <filter name="user_documents" string="Documents"
                        domain="[('res_model', 'not like', 'ir.%'), ('res_model', '!=', False)]"/>
                <group string="Group by">
                    <filter name="group_model" string="Model"
                            context="{'group_by': 'res_model'}"/>
                </group>
            </search>
        </field>
    </record>

    <!-- Top menu item -->
    <menuitem
            id="menu_document_root"
            name="Knowledge"
            groups="knowledge.group_document_user"
            sequence="116"/>

    <menuitem
            id="menu_document_section"
            name="Documents"
            groups="knowledge.group_document_user"
            parent="menu_document_root"/>

    <menuitem
            id="menu_document"
            name="Documents"
            action="knowledge_action_documents"
            parent="menu_document_section"/>

</odoo>