[Clarification] Version update for spring-boot no longer include a required package.

[jimflores5]

From a NWA student comment in the errata channel:
"13. Model Validation
According to Google, the newer versions of spring-boot do not include the required package for validation annotations.
Must add "implementation 'org.springframework.boot:spring-boot-starter-validation'" to the dependencies in the build.gradle file."

https://launchcodelc101nwa.slack.com/archives/C01C0N0FAHZ/p1615135215014100