Add sample code for website documentation

Author: acogoluegnes

src/test/java/com/rabbitmq/client/amqp/docs/WebsiteDocumentation.java

@@ -1,5 +1,6 @@
 package com.rabbitmq.client.amqp.docs;
 
+import static com.rabbitmq.client.amqp.ConnectionSettings.Affinity.Operation.PUBLISH;
 import static java.nio.charset.StandardCharsets.UTF_8;
 
 import java.time.Duration;
@@ -375,4 +376,15 @@ void combinedFilterExpressions() {
         })
         .build();
   }
+
+  void affinity() {
+    Environment environment = null;
+    Connection connection = environment.connectionBuilder()
+        .affinity()
+            .queue("my-queue")
+            .operation(PUBLISH)
+            .reuse(true)
+        .connection()
+        .build();
+  }
 }