docs: Update README.md (#2334)

Corrected quote from Wikipedia.

decorator/README.md

@@ -35,7 +35,8 @@ Wikipedia says
 > be added to an individual object, either statically or dynamically, without affecting the behavior 
 > of other objects from the same class. The decorator pattern is often useful for adhering to the 
 > Single Responsibility Principle, as it allows functionality to be divided between classes with 
-> unique areas of concern.
+> unique areas of concern as well as to the Open-Closed Principle, by allowing the functionality 
+> of a class to be extended without being modified.
 
 **Programmatic Example**