ated by kramdown in Jekyll

    Optional Parameters:
      * beforeHeading (bool)   : false  - Set to true if the anchor should be placed _before_ the heading's content
      * anchorAttrs   (string) :  ''    - Any custom HTML attributes that will be added to the `<a>` tag; you may NOT use `href`, `class` or `title`;
                                          the `%heading%` placeholder is available
      * anchorBody    (string) :  ''    - The content that will be placed inside the anchor; the `%heading%` p