Update README.md

Increase clarity

private-class-data/README.md

@@ -66,7 +66,7 @@ public class Stew {
 }
 ```
 
-Now, we have ImmutableStew class, where its ingredient is protected by StewData class so methods are unable to manipulate the data of the stew.
+Now, we have ImmutableStew class, where its data is protected by StewData class. Now, the methods in are unable to manipulate the data of the ImmutableStew class.
 ```
 public class StewData {
   private final int numPotatoes;