title: How do I automatically link to a parameter type in ReST docstrings in Sphinx?
body: <p>For example, I have the following code:</p>
  
  <pre><code># Solve for coefficients of quadratic approximation
  def quad(p, x):
      """Solves for the coefficients of the quadratic approximation of a
      polynomial ``p`` at points ``x``.
  
      :param :cls:`numpy.polynomial.Polynomial` p:
          The polynomial to be approximated by a quadratic function.
      :param list x:
          The three points along which the quadratic function is to be fitted.
      """
  </code></pre>
  
  <p>Notice the part where I say <code>:cls:<code>numpy.polynomial.Polynomial</code></code>. How do I make that link directly to the documentation for the <code>numpy.polynomial.Polynomial</code> class?</p>