docs(microservices): add docs about record builders

Author: kamilmysliwiec

content/microservices/mqtt.md

@@ -115,3 +115,15 @@ getTemperature(context) {
   console.log(`Topic: ${context.getTopic()}`);
 }
 ```
+
+#### Record builders
+
+To configure message options, you can use the `MqttRecordBuilder` class. For example, to set `QoS` to `2` use the `setQoS` method, as follows:
+
+```typescript
+const message = { event: 'USER_CREATED' };
+const record = new MqttRecordBuilder(message).setQoS(2).build();
+this.client.send('notifications', record).subscribe(...);
+```
+
+> info **Hint** `MqttRecordBuilder` class is exported from the `@nestjs/microservices` package.

content/microservices/nats.md

@@ -125,3 +125,21 @@ getDate(data, context) {
   return new Date().toLocaleTimeString(...);
 }
 ```
+
+#### Record builders
+
+To configure message options, you can use the `NatsRecordBuilder` class. For example, to add `x-version` header, use the `setHeaders` method, as follows:
+
+```typescript
+import * as nats from 'nats';
+
+// somewhere in your code
+const headers = nats.headers();
+headers.set('x-version', '1.0.0');
+
+const message = { event: 'USER_CREATED' };
+const record = new NatsRecordBuilder(message).setHeaders(headers).build();
+this.client.send('notifications', record).subscribe(...);
+```
+
+> info **Hint** `NatsRecordBuilder` class is exported from the `@nestjs/microservices` package.

content/microservices/rabbitmq.md

@@ -195,3 +195,23 @@ getNotifications(data, context) {
   channel.ack(originalMsg);
 }
 ```
+
+#### Record builders
+
+To configure message options, you can use the `RmqRecordBuilder` class. For example, to set `headers` and `priority` properties, use the `setOptions` method, as follows:
+
+```typescript
+const message = { event: 'USER_CREATED' };
+const record = new RmqRecordBuilder(message)
+  .setOptions({
+    headers: {
+      ['x-version']: '1.0.0',
+    },
+    priority: 3,
+  })
+  .build();
+
+this.client.send('notifications', record).subscribe(...);
+```
+
+> info **Hint** `RmqRecordBuilder` class is exported from the `@nestjs/microservices` package.