title: Can type hint in python 3 be used to generate docstring?
body: <p>We can indicate the types of function parameters using docstring in python:</p>
  
  <pre><code>def f1(a):
      """
      :param a: an input.
      :type a: int
      :return: the input integer.
      :rtype: int
      """
      return a
  </code></pre>
  
  <p>For <code>f1</code>, autodoc generates the following document:</p>
  
  <pre><code>fun1(a)
      Parameters : a (int) – an input.
      Returns    : the input integer.
      Return type: int
  </code></pre>
  
  <p>In python 3, the types can be indicated by type hint as well:</p>
  
  <pre><code>def f2(a: int):
      """
      :param a: an input.
      :return: the input integer.
      :rtype: int
      """
      return a
  </code></pre>
  
  <p>When we run autodoc, it puts the type by the parameter declaration, but not in the description:</p>
  
  <pre><code>f2(a: int)
      Parameters : a – an input.
      Returns    : the input integer.
      Return type: int
  </code></pre>
  
  <p>Would it be possible to generate the documentation as <code>f1</code> using annotation instead of docstring? I'm using python 3.6. Thank you!</p>