Update response to fusaka

Author: marcindsobczak

src/testing/testing_buildBlockV1.md

@@ -15,7 +15,7 @@ This method is considered sensitive and is intended for testing environments onl
 
 ### Response
 
-* result: `OBJECT` - instance of [`engine_getPayloadV4`](../engine/prague.md#response-1)
+* result: `OBJECT` - instance of [`engine_getPayloadV5`](../engine/osaka.md#response)
 * error: code and message set in case an exception happens while building the requested block.
 
 ### Specification