Update README.md (#333)

Author: Reuven Harrison

README.md

@@ -12,6 +12,7 @@ Licensed under the [MIT License](LICENSE).
 The project has received pull requests from many people. Thanks to everyone!
 
 Here's some projects that depend on _kin-openapi_:
+  * [https://github.com/Tufin/oasdiff](https://github.com/Tufin/oasdiff) - "A diff tool for OpenAPI Specification 3"
   * [github.com/getkin/kin](https://github.com/getkin/kin) - "A configurable backend"
   * [github.com/danielgtaylor/apisprout](https://github.com/danielgtaylor/apisprout) - "Lightweight, blazing fast, cross-platform OpenAPI 3 mock server with validation"
   * [github.com/deepmap/oapi-codegen](https://github.com/deepmap/oapi-codegen) - Generate Go server boilerplate from an OpenAPI 3 spec