added facade to the main readme

Author: AdelDaniel

README.md

@@ -1,7 +1,7 @@
 # Dart Programming Language 
 
 ## OOP 
-- <strong><a href="1_oop/README.md" target="_blank">What Is OOP ?!</a></strong>
+- <strong><a href="1_oop/" target="_blank">What Is OOP ?!</a></strong>
 
 ## Design Patterns 
      reusable solution to a commonly occurring problem within a given context in software design.
@@ -57,7 +57,9 @@
         - Concept of inheritance is used to compose interfaces and define ways to compose objects to obtain new functionalities.
 
 
-    - <strong><a href="structural_design_pattern/Adapter/README.md" target="_blank">Adapter</a></strong>
+    - <strong><a href="structural_design_pattern/Adapter/" target="_blank">Adapter</a></strong>
 
-    - <strong><a href="structural_design_pattern/bridge/README.md" target="_blank">Bridge</a></strong>
+    - <strong><a href="structural_design_pattern/bridge/" target="_blank">Bridge</a></strong>
+
+    - <strong><a href="structural_design_pattern/facade/" target="_blank">Facade</a></strong>