Add a link to Japanese eBook (REST API のためのコード生成入門 (OpenAPI Generator)) (#3280)

Author: wing328

README.md

@@ -597,6 +597,7 @@ Here are some companies/projects (alphabetical order) using OpenAPI Generator in
 - 2019-05-22 - [REST APIs代码生成指南(OpenAPI Generator)](https://gum.co/openapi_generator_ebook_gb) by [William Cheng](https://twitter.com/wing328), [Xin Meng](https://github.com/xmeng1)
 - 2019-05-24 - [REST API 代碼生成指南 (OpenAPI Generator)](https://gum.co/openapi_generator_ebook_big5) by [William Cheng](https://twitter.com/wing328)
 - 2019-06-24 - [Kubernetes Clients and OpenAPI Generator](https://speakerdeck.com/wing328/kubernetes-clients-and-openapi-generator) by [William Cheng](https://twitter.com/wing328) at [Kubernetes Contributor Summits Shanghai 2019](https://www.lfasiallc.com/events/contributors-summit-china-2019/)
+- 2019-07-04 - [REST API のためのコード生成入門 (OpenAPI Generator)](https://gum.co/openapi_generator_ebook_big5) by [William Cheng](https://twitter.com/wing328), [中野暁人](https://github.com/ackintosh), [和田拓朗](https://github.com/taxpon)
 
 ## [6 - About Us](#table-of-contents)