Update README

[sabdinu]

Is your feature request related to a problem? Please describe.

The README is documenting the possibility to authenticate through user impersonation, which has been communicated by the Omnia Industrial IIoT team that it is outdated.

Describe the solution you'd like

Update the README with the current authentication options.

Describe alternatives you've considered

Additional context

[franktore]

Looking into it. README will be updated to reflect latest library version.