Document Lifecycle change of DefaultMessageListenerContainer.

See #5078
Original pull request #5080

src/main/antora/modules/ROOT/pages/migration-guide/migration-guide-4.x-to-5.x.adoc

@@ -62,6 +62,10 @@ static class Config extends AbstractMongoClientConfiguration {
 
 Users upgrading from prior versions may choose `BigDecimalRepresentation.STRING` as default to retain previous behaviour.
 
+== DefaultMessageListenerContainer auto startup
+
+The `DefaultMessageListenerContainer` that can be used to listen to e.g. _Change Streams_ now defaults its `SmartLifecycle` auto startup to `true`.
+
 == JMX Support Discontinued.
 
 We recommend switching to Spring Boot https://docs.spring.io/spring-boot/reference/actuator/endpoints.html[Actuator Endpoints].

src/main/antora/modules/ROOT/pages/mongodb/change-streams.adoc

@@ -44,6 +44,8 @@ container.stop();
 <5> Do not forget to stop the container once you are sure you no longer need it. Doing so stops all running `Task` instances within the container.
 ====
 
+`DefaultMessageListenerContainer` implements `SmartLifecycle` and will by default be automatically started when registered as a Bean in the Application Context.
+
 [NOTE]
 ====
 Errors while processing are passed on to an `org.springframework.util.ErrorHandler`. If not stated otherwise a log appending `ErrorHandler` gets applied by default. +