docs(README): change wording from specification to definition (#2983)

Author: ponelat

README.md

@@ -6,7 +6,7 @@
 
 **🕰️ Looking for the older version of Swagger Editor?** Refer to the [*2.x* branch](https://github.com/swagger-api/swagger-editor/tree/2.x).
 
-Swagger Editor lets you edit [Swagger API specifications](https://github.com/swagger-api/swagger-spec/blob/master/versions/2.0.md) in YAML inside your browser and to preview documentations in real time.
+Swagger Editor lets you edit [OpenAPI API definitions](https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.0.3.md) in YAML inside your browser and to preview documentations in real time.
 Valid Swagger JSON descriptions can then be generated and used with the full Swagger tooling (code generation, documentation, etc).
 
 As a brand new version, written from the ground up, there are some known issues and unimplemented features. Check out the [Known Issues](#known-issues) section for more details.