OAuth2 Official resource has a lot of deprecated code

### Roadmap URL

https://roadmap.sh/spring-boot

### Suggestions

In the `OAuth2` topic, the first [resource](https://spring.io/guides/tutorials/spring-boot-oauth2/) has a lot of deprecated code starting [here](https://spring.io/guides/tutorials/spring-boot-oauth2#_making_the_home_page_public), so it's not really a good resource to follow through.