Update README.md

Author: shockey

README.md

@@ -22,7 +22,8 @@ The OpenAPI Specification has undergone 4 revisions since initial creation in 20
 
 Swagger UI Version | Release Date | OpenAPI Spec compatibility | Notes | Status
 ------------------ | ------------ | -------------------------- | ----- | ------
-3.1.2              | 2017-07-31   | 2.0                        | [tag v3.1.2](https://github.com/swagger-api/swagger-ui/tree/v3.1.2) |
+3.1.2              | 2017-07-31   | 2.0, 3.0                   | [tag v3.1.2](https://github.com/swagger-api/swagger-ui/tree/v3.1.2) |
+3.0.21              | 2017-07-26   | 2.0                        | [tag v3.0.21](https://github.com/swagger-api/swagger-ui/tree/v3.0.21) |
 2.2.10             | 2017-01-04   | 1.1, 1.2, 2.0              | [tag v2.2.10](https://github.com/swagger-api/swagger-ui/tree/v2.2.10) |
 2.1.5              | 2016-07-20   | 1.1, 1.2, 2.0              | [tag v2.1.5](https://github.com/swagger-api/swagger-ui/tree/v2.1.5) |
 2.0.24             | 2014-09-12   | 1.1, 1.2 | [tag v2.0.24](https://github.com/swagger-api/swagger-ui/tree/v2.0.24) |