knowledge/document_page_approval/security/document_page_security.xml

<?xml version="1.0" encoding="utf-8"?>
<openerp>
<data noupdate="0">
    <record id="base.group_document_approver_user" model="res.groups">
        <field name="name">Document approver</field>
        <field name="users" eval="[(4, ref('base.user_root'))]"/>
    </record>
</data>
</openerp>