ZCML File
configure.zcml

<configure
    xmlns:apidoc="http://namespaces.zope.org/apidoc"
    xmlns:zcml="http://namespaces.zope.org/zcml"
    i18n_domain="zope"
    >
<apidoc:bookchapter
    id="viewlet"
    title="Viewlets and Viewlet Managers"
    doc_path="README.txt"
    zcml:condition="have apidoc"
    />
<apidoc:bookchapter
    id="directives"
    title="Viewlet-related ZCML Directives"
    doc_path="directives.txt"
    parent="viewlet"
    zcml:condition="have apidoc"
    />
</configure>