docs: add comprehensive documentation for exchange examples

- Add detailed doc comments explaining the direct exchange example, including steps and expected output
- Add detailed doc comments explaining the fanout exchange example, including steps and expected output

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

Author: appleboy

example_test.go

@@ -9,7 +9,32 @@ import (
 	"github.com/golang-queue/queue/core"
 )
 
-// Direct Exchange
+/*
+Example_direct_exchange demonstrates how to use RabbitMQ with a direct exchange.
+This example creates two workers (w1, w2) that both listen to the same queue and exchange,
+and a producer that sends multiple messages to the queue. The workers process the messages
+in a round-robin fashion.
+
+Steps:
+1. Create a mock message to be sent.
+2. Initialize worker w1 with a direct exchange and queue, and define its processing function.
+3. Start a queue (q1) with worker w1.
+4. Initialize worker w2 with the same direct exchange and queue, and define its processing function.
+5. Start a queue (q2) with worker w2.
+6. Create a producer worker (w) with the same exchange and routing key.
+7. Start a queue (q) with the producer worker.
+8. Send the mock message to the queue multiple times.
+9. Wait for processing, then release all queues.
+
+Expected Output:
+- The two workers alternately print the received message.
+
+Unordered Output:
+worker01 get data: foo
+worker02 get data: foo
+worker01 get data: foo
+worker02 get data: foo
+*/
 func Example_direct_exchange() {
 	m := mockMessage{
 		Message: "foo",
@@ -92,7 +117,30 @@ func Example_direct_exchange() {
 	// worker02 get data: foo
 }
 
-// Fanout Exchange
+/*
+Example_fanout_exchange demonstrates how to use RabbitMQ with a fanout exchange.
+This example creates two workers (w1, w2) each listening to a different queue bound to the same
+fanout exchange, and a producer that sends a message to the exchange. Both workers receive and
+process the same message.
+
+Steps:
+1. Create a mock message to be sent.
+2. Initialize worker w1 with a unique queue and the fanout exchange, and define its processing function.
+3. Start a queue (q1) with worker w1.
+4. Initialize worker w2 with a different queue and the same fanout exchange, and define its processing function.
+5. Start a queue (q2) with worker w2.
+6. Create a producer worker (w) with the same fanout exchange.
+7. Start a queue (q) with the producer worker.
+8. Send the mock message to the exchange.
+9. Wait for processing, then release all queues.
+
+Expected Output:
+- Both workers print the received message.
+
+Unordered Output:
+worker01 get data: foo
+worker02 get data: foo
+*/
 func Example_fanout_exchange() {
 	m := mockMessage{
 		Message: "foo",