Add a link to article in GiFT, Inc (#5275)

Author: wing328

README.md

@@ -722,6 +722,7 @@ Here are some companies/projects (alphabetical order) using OpenAPI Generator in
 - 2019-12-04 - [Angular＋NestJS＋OpenAPI（Swagger）でマイクロサービスを視野に入れた環境を考える](https://qiita.com/teracy55/items/0327c7a170ec772970c6) by [てらしー](https://twitter.com/teracy55)
 - 2019-12-17 - [OpenAPI Generator で OAuth2 アクセストークン発行のコードまで生成してみる](https://www.techscore.com/blog/2019/12/17/openapi-generator-oauth2-accesstoken/) by [TECHSCORE](https://www.techscore.com/blog/)
 - 2019-12-23 - [Use Ada for Your Web Development](https://www.electronicdesign.com/technologies/embedded-revolution/article/21119177/use-ada-for-your-web-development) by [Stephane Carrez](https://github.com/stcarrez)
+- 2019-12-23 - [OpenAPIのスキーマを分割・構造化していく方法](https://gift-tech.co.jp/articles/structured-openapi-schema) by [小飯塚達也](https://github.com/t2h5) at [GiFT, Inc](https://gift-tech.co.jp/)
 - 2020-01-17 - [OpenAPI demo for Pulp 3.0 GA](https://www.youtube.com/watch?v=mFBP-M0ZPfw&t=178s) by [Pulp](https://www.youtube.com/channel/UCI43Ffs4VPDv7awXvvBJfRQ) at [Youtube](https://www.youtube.com/)
 - 2020-01-19 - [Why document a REST API as code?](https://dev.to/rolfstreefkerk/why-document-a-rest-api-as-code-5e7p) by [Rolf Streefkerk](https://github.com/rpstreef) at [DEV Community](https://dev.to)
 - 2020-01-28 - [Get Your Serverless Swagger Back with OpenAPI](https://dev.to/matttyler/get-your-serverless-swagger-back-with-openapi-48gc) by [Matt Tyler](https://dev.to/matttyler)