Where is the official Google+ Comments page for the site?

Question

Google Plus

Hello.
There is no official page with information on how to put Google+ Comments on the site. There is only a plugin for WordPress - https://wordpress.org/plugins/gplus-comments/
Installation information can only be obtained from third-party sites.

<script src="https://apis.google.com/js/plusone.js"></script>
<div id="google_comments"></div>
<script>
gapi.comments.render('google_comments', {
    href: window.location,
    width: '650',
    first_party_property: 'BLOGGER',
    view_type: 'FILTERED_POSTMOD'
});
</script>

Is Google hiding this information, or is it preparing to close the feature without opening it?