Update docs/_spec/05-classes-and-objects.md

Author: bishabosha

docs/_spec/05-classes-and-objects.md

@@ -808,7 +808,7 @@ The definition of `F` in the last line is implicitly expanded to
 class F(using iname: ImpliedName) extends
   Object, // implicitly inserted
   ImpliedGreeting(using iname), // implicitly inserted
-  ImpliedFormalGreeting(using iname)
+  ImpliedFormalGreeting
 ```
 Due to rule 4, `F` is required to also extend `ImpliedGreeting` and pass arguments to it, however note that because `ImpliedGreeting` has only context parameters the extension was added implicitly.