docs(crons): Add AspectJ dependency requirement for Spring Boot @SentryCheckIn annotation (#15698)

Author: evanpurkhiser

platform-includes/crons/setup/java.spring-boot.mdx

@@ -1,5 +1,11 @@
 If you are using [Quartz](http://www.quartz-scheduler.org/), please see <PlatformLink to="/integrations/quartz/">our Quartz integration</PlatformLink>. You may also [send check-ins manually](/platforms/java/crons/).
 
+<Alert level="info">
+
+The `@SentryCheckIn` annotation requires `org.aspectj:aspectjweaver` to be present as a dependency in your project.
+
+</Alert>
+
 ## Check-Ins (Recommended)
 
 Check-in monitoring allows you to track a job's progress by completing two check-ins: one at the start of your job and another at the end of your job. This two-step process allows Sentry to notify you if your job didn't start when expected (missed) or if it exceeded its maximum runtime (failed). To start sending check-ins simply add the `@SentryCheckIn("<monitor-slug>")` annotation to the method you want to send check-ins for.