title: How can I list the undocumented modules/classes/constants/methods with yardoc?
body: <p>I have a small library of code that I am documenting with <a href="http://yardoc.org/" rel="noreferrer">YARD</a>.  When I run the <code>yardoc</code> command, it tells me:</p>
  
  <pre><code>Files:          40
  Modules:        14 (    0 undocumented)
  Classes:        39 (    0 undocumented)
  Constants:      21 (    4 undocumented)
  Methods:       239 (   31 undocumented)
   88.82% documented
  </code></pre>
  
  <p>Instead of wading through all of my code to find the undocumented constants and methods, I want it to simply list the undocumented items.  Anybody know how to do this?</p>