Add Namsor as the sponsor (#2639)

Add Namsor as the sponsor

README.md

@@ -33,6 +33,15 @@
 
 </div>
 
+## Sponsors
+
+If you find OpenAPI Generator useful for work, please consider asking your company to support this Open Source project by [becoming a sponsor](https://opencollective.com/openapi_generator). You can also individually sponsor the project by [becoming a backer](https://opencollective.com/openapi_generator).
+
+#### Thank you to our bronze sponsors!
+
+[![NamSor](https://openapi-generator.tech/img/companies/namsor.png)](https://www.namsor.com/?utm_source=openapi_generator&utm_medium=github_webpage&utm_campaign=sponsor)
+
+
 ## Overview
 OpenAPI Generator allows generation of API client libraries (SDK generation), server stubs,  documentation and configuration automatically given an [OpenAPI Spec](https://github.com/OAI/OpenAPI-Specification) (both 2.0 and 3.0 are supported). Currently, the following languages/frameworks are supported: