Rm obsolete reference to ADTs

VL2/content/VL2_reiteration.tex

@@ -2,5 +2,4 @@
 \item What is haskell? What are the 3 fundamental concepts behind it?
 \item How do you do pattern matching?
 \item What is the difference between lists and tuples? How do you construct them?
-\item How do you define your own data types?
 \end{itemize}