title: How to add custom taxonomies to the meta fields in yoast SEO?
body: <p>I have a wordpress 4.2.1 based website with Yoast wordpress SEO plugin. In this site I have several custom posts types such as "publications" with some custom taxonomies "keywords, authors" all are made by custom post type UI plugin.
  When viewing the page source of articles published in that custom post type the code shows meta properties like:</p>
  
  <pre><code>&lt;meta property="og:locale" content="fr_FR" /&gt;
  &lt;meta property="og:type" content="article" /&gt;
  &lt;meta property="og:title" content="bla bla bla- Marketing" /&gt;
  &lt;meta property="og:description" content="bla bla bla" /&gt;
  &lt;meta property="og:site_name" content="Marketing" /&gt;
  </code></pre>
  
  <p>Please, how do I make a Yoast SEO plugin show meta properties of custom taxonomies related to such post type?</p>