springboot Update documentation on excluding an auto-configuration to recommend exclude on SpringBootApplication

Updated Spring Boot Doc Sec-3.4.2 to encourage use of SpringBootApplication annotation @wilkinsona . Please review and merge

Comment From: snicoll

@protyay thank you for making your first contribution to Spring Boot. Given that @SpringBootApplication is added on an application (and is a @Configuration already), I've polished the sample a little bit more.

Comment From: protyay

@snicoll Thanks.