title: link to Ruby core class in YARD
body: <p>In YARD, when the parameter type or return type is a class in the same project, it automatically creates a link to the page of that class. Now I want to do the same to a Ruby core class (or any external class), says <code>Integer</code>. I want YARD to link any <code>Integer</code> type to <a href="http://ruby-doc.org/core-2.2.3/Integer.html" rel="nofollow">http://ruby-doc.org/core-2.2.3/Integer.html</a>. Generally I want YARD to try to link</p>
  
  <pre><code>"http://ruby-doc.org/core-2.2.3/#{cls.name}.html"
  </code></pre>
  
  <p>if <code>cls</code> is not local to my project. Is that possible with YARD?</p>
  
  <p>For guys familiar with Java, I am trying to do something like <a href="http://docs.oracle.com/javase/8/docs/technotes/tools/windows/javadoc.html#CHDEDJFI" rel="nofollow">the <code>-link</code> option of Javadoc</a>.</p>