title: How to document struct data members outside of struct
body: <p>When I document a function with Doxygen I can do this:</p>
  
  <pre><code>/*!
   * @brief does something
   * @param a first parameter
   *
   * Longer description
   */
  void foo(int a) { /* */ }
  </code></pre>
  
  <p>But is there way I can document struct members this way:</p>
  
  <pre><code>/*!
   * @brief a struct
   * @??? a first struct member
   * @??? b second struct member
   *
   * Longer description
   */
  struct a 
  {
      int a,
      int b,
  };
  </code></pre>
  
  <p>The reason is, I want to avoid having to document my struct members with inline comments, if possible.</p>