code: function include (filename, language) {
    return fs.readFile(filename, 'utf-8').then(function (contents) {
      return '```' +
        (typeof language === 'string' ? language : path.extname(filename).substr(1)) +
        '\n' +
        contents +
        '\n```\n'
    })
  }
docs: Include a file into a markdown code-block
  
  @param filename
  @param language the programming language used for the code-block
  @returns {string}
  @access public
  @memberOf helpers