Drop classic config examples for OAuth 2, minor edits
Drop classic config examples for OAuth 2, minor edits

This feature is 3.8-specific and we have new style
configuration schema support, so why bother.

rabbitmq/rabbitmq-website,rabbitmq/rabbitmq-website,rabbitmq/rabbitmq-website,rabbitmq/rabbitmq-website,rabbitmq/rabbitmq-website