docs: document producer-consumer example with RabbitMQ in README

- Add README for the producer-consumer example with RabbitMQ
- Include prerequisites, installation steps, and running instructions for both producer and consumer

Signed-off-by: appleboy <[email protected]>

Author: appleboy

_example/producer-consumer/README.md

@@ -0,0 +1,65 @@
+# Producer-Consumer Example with RabbitMQ
+
+This example demonstrates a simple producer-consumer pattern using RabbitMQ in Go.
+
+## Prerequisites
+
+- Go 1.22 or later
+- RabbitMQ server
+
+## Installation
+
+1. Clone the repository:
+
+```sh
+git clone https://github.com/appleboy/golang-queue.git
+cd golang-queue/rabbitmq/_example/producer-consumer
+```
+
+2. Install dependencies:
+
+```sh
+go mod tidy
+```
+
+## Running the Example
+
+### Start RabbitMQ
+
+Ensure RabbitMQ server is running. You can start RabbitMQ using Docker:
+
+```sh
+docker run -d --name rabbitmq -p 5672:5672 -p 15672:15672 rabbitmq:3-management
+```
+
+### Producer
+
+The producer sends messages to the RabbitMQ queue.
+
+1. Navigate to the producer directory:
+
+```sh
+cd producer
+```
+
+2. Run the producer:
+
+```sh
+go run main.go
+```
+
+### Consumer
+
+The consumer receives messages from the RabbitMQ queue.
+
+1. Navigate to the consumer directory:
+
+```sh
+cd consumer
+```
+
+2. Run the consumer:
+
+```sh
+go run main.go
+```