Fix rails middleware list in api_app guide [ci skip]

[yhirano55]

Summary

It seems that middleware list on api-mode is different from actual result:

$ bin/rails middleware
use Rack::Sendfile
use ActionDispatch::Static
use ActionDispatch::Executor
use ActiveSupport::Cache::Strategy::LocalCache::Middleware
use Rack::Runtime
use ActionDispatch::RequestId
use ActionDispatch::RemoteIp
use Rails::Rack::Logger
use ActionDispatch::ShowExceptions
use ActionDispatch::DebugExceptions
use ActionDispatch::Reloader
use ActionDispatch::Callbacks
use ActiveRecord::Migration::CheckPending
use Rack::Head
use Rack::ConditionalGet
use Rack::ETag
run MyApi::Application.routes

• MyApi::Application::Routes is a rack application, not a middleware. So I removed it.

[rails-bot]

r? @rafaelfranca

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[kamipo]

MyApi::Application.routes is an app, not a middleware. It should be removed in the list I think.

[yhirano55]

Oh… you're right. I'll remove it.

[yhirano55]

@kamipo I removed it. please review it again.