How to use the fdoc gem with grape?

Question

Ruby on Rails

Why can't fdoc scfold my documents? Fdoc: https://github.com/square/fdoc Grape: https://github.com/intridea/grape docs/fdoc folders created! app/api/my_api/base.rb
FDOC_SCAFFOLD=true bundle exec rspec spec/api

module Twitter
  class API < Grape::API
    version 'v1', using: :path, vendor: 'twitter'
    format :json

    get :ping do 
      {status: "ok"}
    end

  end
end

gemfile

...
gem 'fdoc'

gem 'rspec'
gem 'rack-test', require: 'rack/test'

spec/spec_helper.rb

ENV['RAILS_ENV'] ||= 'test'
require File.expand_path('../../config/environment', __FILE__)
require 'rspec/rails'
require 'rack/test'
require 'fdoc'

RSpec.configure do |config|
  config.infer_spec_type_from_file_location!
  config.raise_errors_for_deprecations!
  config.infer_base_class_for_anonymous_controllers = false
  config.order = 'random'
end

Example: https://github.com/square/fdoc/blob/master/docs/sc...
My:
spec/api/twiter_spec.rb

require 'spec_helper'
require 'fdoc/spec_watcher'

describe Twitter::API do
  include Fdoc::SpecWatcher

  describe "twitter", :fdoc => '/ping' do
    it "test ping" do
      get "twitter/v1/ping/"
      response.status.should == 200
    end
  end
end

If you don't want to deal with this, please provide a link to a simple and WORKING example of using fdoc.