Document Streaming interface

Author: thekid

README.md

@@ -311,14 +311,22 @@ public class com.amazon.aws.lambda.Environment {
 }
 ```
 
-Lambda
-------
-Instead of functions, a handler's *target()* method may also return instances implementing the *Lambda* interface:
+Interfaces
+----------
+Instead of functions, a handler's *target()* method may also return instances implementing the *Lambda* or *Streaming* interfaces:
 
 ```php
 public interface com.amazon.aws.lambda.Lambda {
   public function process(var $event, com.amazon.aws.lambda.Context $context): var
 }
+
+public interface com.amazon.aws.lambda.Streaming {
+  public abstract function handle(
+    var $event,
+    com.amazon.aws.lambda.Stream $stream,
+    com.amazon.aws.lambda.Context $context
+  ): void
+}
 ```
 
 See also