Correct code example (quii#772)

generics.md

@@ -550,7 +550,7 @@ Not many people complain about our ability to define interfaces which, like gene
 When you consider that if you've used arrays, slices or maps; you've _already been a consumer of generic code_.
 
 ```
-var myApples []Apples
+var myApples []Apple
 // You can't do this!
 append(myApples, Orange{})
 ```