Missing required parameters in credential issuer metadata example

[jtalir]

Section "Credential Issuer Metadata Parameters" concludes with the example of metadata that has only single parameter "credential_configurations_supported". Based on the list of parameters at the beginning of the section, every metadata should also have required parameters credential_issuer and credential_endpoint. Even though example is non-normative, it would be easier for the reader to have example compliant with spec.