Update id_token example to correctly show nested jwt

[perlboy]

Description

As per OIDC spec If the ID Token is encrypted, it MUST be signed then encrypted, with the result being a Nested JWT,

Area Affected

Tokens Example

Change Proposed

Update the example to a Nested JWT as specified in the OIDC spec.

[perlboy]

Preamble: Biza currently has 42 open issues within Standards Maintenance. In an effort to optimise our own backlog we are closing those which have no actual response from the DSB. They may be reopened at a later time or referenced when the issues are highlighted by third parties.

The provided ID Token example appears to be completely inaccurate including the presentation of OAuth parameters which would actually be in the token response (not the ID Token).