Add some documentation about LambdaStreamingResponseHandler (langchai…

…n4j#1844)

docs/docs/tutorials/4-response-streaming.md

@@ -64,4 +64,23 @@ model.generate(userMessage, new StreamingResponseHandler<AiMessage>() {
         error.printStackTrace();
     }
 });
+```
+
+A more compact way to stream the response is to use the `LambdaStreamingResponseHandler` class.
+This utility class provides static methods to create a `StreamingResponseHandler` using lambda expressions.
+The way to use lambdas to stream the response is quite simple. 
+You just call the `onNext()` static method with a lambda expression that defines what to do with the token:
+
+```java
+import static dev.langchain4j.model.LambdaStreamingResponseHandler.onNext;
+
+model.generate("Tell me a joke", onNext(System.out::print));
+```
+
+The `onNextAndError()` method allows you to define actions for both the `onNext()` and `onError()` events:
+
+```java
+import static dev.langchain4j.model.LambdaStreamingResponseHandler.onNextAndError;
+
+model.generate("Tell me a joke", onNextAndError(System.out::print, Throwable::printStackTrace));
 ```