Fix two more broken Haddock references

Control/Monad/Error/Class.hs

@@ -77,7 +77,7 @@ from the point an exception is thrown to the point that it is handled.
 
 Is parameterized over the type of error information and
 the monad type constructor.
-It is common to use @'Data.Either' String@ as the monad type constructor
+It is common to use @'Either' String@ as the monad type constructor
 for an error monad in which error descriptions take the form of strings.
 In that case and many other common cases the resulting monad is already defined
 as an instance of the 'MonadError' class.

Control/Monad/Except.hs

@@ -19,7 +19,7 @@ other values are used as inputs to the bound function.
 [Useful for:] Building computations from sequences of functions that may fail
 or using exception handling to structure error handling.
 
-[Example type:] @'Data.Either' String a@
+[Example type:] @'Either' String a@
 
 The Error monad (also called the Exception monad).
 -}