Update README.md

Author: TesteurManiak

README.md

@@ -6,6 +6,7 @@ Some tips and tricks in Flutter & Dart.
 
 # Table of Contents
 
+* [Json Object Model](#json-object-model)
 * [Pump App Tester](#pump-app-tester)
 * [Safe Complete](#safe-complete)
 * [Stream Converter](#stream-converter)
@@ -15,6 +16,12 @@ Some tips and tricks in Flutter & Dart.
 * [Benchmark async method](#benchmark-async-method)
 * [JSON decoding](#json-decoding)
 
+# Json Object Model
+
+[Source Code](source/json_object_model.dart)
+
+![](images/json_object_model.png)
+
 # Pump App Tester
 
 [Source Code](source/pump_app_tester.dart)