title: Insert Post Title into the title tag of thumbnail link
body: <p>This is what I have and I am able to insert the Post Title into the title value of the thumbnail, but instead I want it to be inserted into the title value of the link that is wrapped around it.</p>
  
  <pre><code>add_filter('wp_get_attachment_image_attributes', 'my_img_title', 10, 2);
  function my_img_title($attr, $attachment = null){
      $attr['title'] = get_post($title)-&gt;post_title;
      return $attr;
  }
  </code></pre>