SpringBoot Typos in documentation ("spring-factories" instead of "spring.factories")

Fixes two typos in chapter Database Initialization. META-INF/spring-factories -> META-INF/spring.factories

Closes gh-31199

Comment From: snicoll

@matei-cernaianu thank you for making your first contribution to Spring Boot.

Comment From: matei-cernaianu

@snicoll @wilkinsona Thank you for the opportunity to contribute to my main library. :)