Add RepreZen API Studio to Companies/Projects (#620)

* Add RepreZen API Studio to Companies/Projects

Per discussion with @wing328

* Corrected alphabetical order

Corrected alphabetical order of implementations, in response to review comment from @wing238.

Author: tedepstein

README.md

@@ -419,11 +419,11 @@ Here are some companies/projects (alphabetical order) using OpenAPI Generator in
 - [Bithost GmbH](https://www.bithost.ch)
 - [GMO Pepabo](https://pepabo.com/en/)
 - [Raiffeisen Schweiz Genossenschaft](https://www.raiffeisen.ch)
+- [RepreZen API Studio](https://www.reprezen.com/swagger-openapi-code-generation-api-first-microservices-enterprise-development)
 - [REST United](https://restunited.com)
 - [Telstra](https://dev.telstra.com)
 - [unblu inc.](https://www.unblu.com/)
 
-
 ## [5 - Presentations/Videos/Tutorials/Books](#table-of-contents)
 
 - 2018/05/12 - [OpenAPI Generator - community drivenで成長するコードジェネレータ](https://ackintosh.github.io/blog/2018/05/12/openapi-generator/) by [中野暁人](https://github.com/ackintosh)