Readme updated with a new tutorial and company using OpenAPI Generator (#3566)

Author: anlcnydn

README.md

@@ -550,6 +550,7 @@ Here are some companies/projects (alphabetical order) using OpenAPI Generator in
 - [CAM](https://www.cam-inc.co.jp/)
 - [Camptocamp](https://www.camptocamp.com/en)
 - [codecentric AG](https://www.codecentric.de/)
+- [Commencis](https://www.commencis.com/)
 - [Cupix](https://www.cupix.com/)
 - [DB Systel](https://www.dbsystel.de)
 - [FormAPI](https://formapi.io/)
@@ -594,6 +595,7 @@ Here are some companies/projects (alphabetical order) using OpenAPI Generator in
 - 2018/12/09 - [openapi-generator をカスタマイズする方法](https://qiita.com/watiko/items/0961287c02eac9211572) by [@watiko](https://qiita.com/watiko)
 - 2019/01/03 - [Calling a Swagger service from Apex using openapi-generator](https://lekkimworld.com/2019/01/03/calling-a-swagger-service-from-apex-using-openapi-generator/) by [Mikkel Flindt Heisterberg](https://lekkimworld.com)
 - 2019/01/13 - [OpenAPI GeneratorでRESTful APIの定義書から色々自動生成する](https://ky-yk-d.hatenablog.com/entry/2019/01/13/234108) by [@ky_yk_d](https://twitter.com/ky_yk_d)
+- 2019/01/20 - [Contract-First API Development with OpenAPI Generator and Connexion](https://medium.com/commencis/contract-first-api-development-with-openapi-generator-and-connexion-b21bbf2f9244) by [Anil Can Aydin](https://github.com/anlcnydn)
 - 2019/01/30 - [Rapid Application Development With API First Approach Using Open-API Generator](https://dzone.com/articles/rapid-api-development-using-open-api-generator) by [Milan Sonkar](https://dzone.com/users/828329/milan_sonkar.html)  
 - 2019/02/02 - [平静を保ち、コードを生成せよ 〜 OpenAPI Generator誕生の背景と軌跡 〜](https://speakerdeck.com/akihito_nakano/gunmaweb34) by [中野暁人](https://github.com/ackintosh) at [Gunma.web #34 スキーマ駆動開発](https://gunmaweb.connpass.com/event/113974/)
 - 2019/02/20 - [An adventure in OpenAPI V3 code generation](https://mux.com/blog/an-adventure-in-openapi-v3-api-code-generation/) by [Phil Cluff](https://mux.com/blog/author/philc/)