Document audience support in Oauth2 resource server

[snicoll]

See #29084 (comment)

[bikash30851]

@snicoll I want to work on it and do the documentation, in what page should the documentation go?

[snicoll]

Thanks for the offer @bikash30851. The documentation for Spring Security is located in spring-boot-project/spring-boot-docs.

[bikash30851]

Perfect, I will start working on it.

[izeye]

This seems to have been resolved via #35286.

[wilkinsona]

Thanks, @izeye!