Add the rabbitmq module

README.md

@@ -8,6 +8,13 @@ module's `scripts/run-all.sh`, never typed by hand.
 | Module | Article | What it demonstrates |
 |---|---|---|
 | [`kafka-basics/`](kafka-basics/README.md) | [Spring Boot 4.1 and Apache Kafka: Producer, Consumer and Serialisation from Scratch](https://ankurm.com/spring-boot-4-1-kafka-producer-consumer-serialisation/) | The on-ramp: what the starter gives you, the two Jackson serializer families, where a key lands and why, and which defaults are Kafka's rather than Spring's |
+| [`rabbitmq/`](rabbitmq/README.md) | [Spring Boot and RabbitMQ: Exchanges, Queues, Bindings and a Working Dead-Letter Queue](https://ankurm.com/spring-boot-rabbitmq-exchanges-dead-letter-queue/) | All four exchange types against a real broker, manual acknowledgement, and a dead-letter path exercised through both rejection and TTL expiry |
+
+The two brokers make an instructive pair. Kafka's consumer holds an offset and the broker
+remembers nothing about individual records; RabbitMQ's broker owns the message until it is
+acknowledged and can route, expire and dead-letter it on its own. Almost every difference in how
+you handle failure follows from that one sentence — which is why Kafka needs a retry topic
+to do what RabbitMQ does with a queue argument.
 
 They are meant to be read in order. `kafka-basics` establishes that the default acknowledgement
 mode is `BATCH` and therefore that delivery is at-least-once; everything the error-handling