[Openid-specs-ab] Add openid_configuration to basic profile

[Torsten Lodderstedt]

Hi all,

during the OpenID workshop at IIW it became apparent that most OPs expect RPs to use the openid configuration to dynamically determine the OPs endpoints and properties. In my opinion this makes a lot of sense as it allows the OP to easier manage changes to those aspects.

I therefore would like to propose to add an explanation of the way this part of OIDC discovery works to the basic client profile document and potentially also make use of the OpenID configuration mandatory for RPs.

kind regards,
Torsten.