Update "Include" tutorial to include gateway header in 404 response

Author: predic8

distribution/src/test/java/com/predic8/membrane/tutorials/advanced/IncludeTutorialTest.java

@@ -54,13 +54,14 @@ void ordersApiReturnsOrderList() {
     }
 
     @Test
-    void unknownPathReturns404() {
+    void unknownPathReturns404WithGatewayHeader() {
         // @formatter:off
         given()
         .when()
             .get("http://localhost:2000/unknown")
         .then()
-            .statusCode(404);
+            .statusCode(404)
+            .header("X-Gateway", equalTo("Membrane"));
         // @formatter:on
     }
 }

distribution/tutorials/advanced/95-Include.yaml

@@ -23,7 +23,8 @@
 # 4.) Call an unknown path:
 #     curl -i http://localhost:2000/unknown
 #
-#     HTTP/1.1 404 Not Found
+#     X-Gateway: Membrane
+#     404 Not Found
 
 # Included files define the per-service APIs.
 include: