SpringBoot Update documentation to reflect Hibernate's CamelCaseToUnderscoresNamingStrategy now being used by default

Some updates to the documentation were missed as part of https://github.com/spring-projects/spring-boot/issues/27352. The section on configuring Hibernate's naming strategy should be updated to reflect that Hibernate's CamelCaseToUnderscoresNamingStrategy is now used by default. The code snippet looks fine, but the surrounding text needs to be updated.