Update main README.md.

Author: ilopX

README.md

@@ -22,7 +22,7 @@ It contains **Dart** examples for all classic **GoF** design patterns.
     - [ ] [**Visitor**](https://refactoring.guru/design-patterns/visitor)
     - [ ] [**Strategy**](https://refactoring.guru/design-patterns/strategy)
 - [ ] **Structural**
-    - [x] [**Adapter**](https://refactoring.guru/design-patterns/adapter) - [[Text Graphics](https://github.com/RefactoringGuru/design-patterns-dart/tree/master/patterns/adapter/text_graphics)] [[Square Round conflict](https://github.com/RefactoringGuru/design-patterns-dart/tree/master/patterns/adapter/square_round_conflict)] 
+    - [x] [**Adapter**](https://refactoring.guru/design-patterns/adapter) - [[Text Graphics](https://github.com/RefactoringGuru/design-patterns-dart/tree/master/patterns/adapter/text_graphics)] [[Square Round conflict](https://github.com/RefactoringGuru/design-patterns-dart/tree/master/patterns/adapter/square_round_conflict)] [[Flutter Adapter](https://github.com/RefactoringGuru/design-patterns-dart/tree/master/patterns/adapter/flutter_adapter)] 
     - [x] [**Bridge**](https://refactoring.guru/design-patterns/bridge) - [[Remote Device Control](https://github.com/RefactoringGuru/design-patterns-dart/tree/master/patterns/bridge/devices_remote_control)] [[Clock](https://github.com/RefactoringGuru/design-patterns-dart/tree/master/patterns/bridge/clock)] 
     - [x] [**Composite**](https://refactoring.guru/design-patterns/composite) - [[Image Editor](https://github.com/RefactoringGuru/design-patterns-dart/tree/master/patterns/composite/image_editor)] [[Products and Boxes](https://github.com/RefactoringGuru/design-patterns-dart/tree/master/patterns/composite/products_and_boxes)] 
     - [x] [**Decorator**](https://refactoring.guru/design-patterns/decorator) - [[Data Source Decoder](https://github.com/RefactoringGuru/design-patterns-dart/tree/master/patterns/decorator/data_source_decoder)]