As auto-configuration for Spring Security OAuth has been removed
from Spring Boot 2.0 and Spring Security 5 doesn't have OAuth
2.0 Authorization / Resource Server support yet, it has not
been obvious at all how to implement an OAUth 2.0 server with
Spring Boot 2.0.

For that reason, this new section briefly explains the current
temporary situation and points to the spring-security-oauth2-autoconfigure
module that restores the auto-configuration support for OAuth
2.0 Authorization and Resource Servers.

Closes gh-12491