Registration - 2.1 - token_endpoint_auth_type description

[gffletch]

It would be very helpful to have a reference to section 2.2.1 of the Messages specification in this description.

The requested authentication type for the Token Endpoint. The options are client_secret_post, client_secret_basic, client_secret_jwt, and private_key_jwt (see section 2.2.1 of Messages for additional descriptions of these values).

[John Bradley]

re #486 add reference to messages 2.2.1 for token_endpoint_supported_auth_types

→ 0bf059003ede

[John Bradley]

Fixes #486 add ref to messages 2.2.1 to token_endpoint_auth_type

→ 6b92815bbc84