function contentDisposition(filename, options) {
  var opts = options || {}

  // get type
  var type = opts.type || 'attachment'

  // get parameters
  var params = createparams(filename, opts.fallback)

  // format into string
  return format(new ContentDisposition(type, params))
}
Create an attachment Content-Disposition header.

@param {string} [filename]
@param {object} [options]
@param {string} [options.type=attachment]
@param {string|boolean} [options.fallback=true]
@return {string}
@api public