Tutorial for the generation of OpenAPI and Swagger UI

[GuentherJulian]

Create tutorials that show how to create the OpenAPI specification and Swagger UI from REST APIs.
Currently there is a PR in devon4j that describes the generation (devonfw/devon4j#490). It would be helpful to have some real example in a tutorial that shows that process.
One tutorial for the Smallrye OpenAPI extension and one how to do it with the Servicedocgen maven plugin.

[GuentherJulian]

Closed with merge of https://github.com/devonfw-tutorials/tutorials/pull/189/files