add @lyrixx rector rule for openapi context

Author: soyuka

core/upgrade-guide.md

@@ -138,3 +138,9 @@ defaults:
 ```
 
 As this is an `extraProperties` it's configurable per resource/operation. This is improving the compatibility of Hydra errors with JSON problem. It also enables new extension points on [Errors](https://api-platform.com/docs/v3.2/core/errors/) such as [Error provider](https://api-platform.com/docs/v3.2/guides/error-provider/) and [Error Resource](https://api-platform.com/docs/v3.2/guides/error-resource/).
+
+### OpenApi context
+
+You may want to convert your openApiContext to openapi, doing so is quite fastidious, @lyrixx created a rector script to help if needed:
+
+https://github.com/lyrixx/rector-apip-openapi