Fix links to Swaggerhub

[samuelmr]

The README links to old versions of the OpenAPI specification:
https://app.swaggerhub.com/apis-docs/SphereonInt/OpenIDFederationAdminServer/0.1.0-d41
https://app.swaggerhub.com/apis-docs/SphereonInt/OpenIDFederationServer/0.1.0-d41

Correct addresses may be
https://app.swaggerhub.com/apis/4Sure/OpenIDFederationAdminServer/
https://app.swaggerhub.com/apis/4Sure/OpenIDFederationServer/