Update README.md

Author: briandoyle81

README.md

@@ -62,6 +62,8 @@ Navigate into the `names` directory. Here you will find two text files containin
 
 Six seconds is an eternity so you've been tasked with speeding up the code. Can you get the runtime to under a second? Under one hundredth of a second?
 
+*You may not use the built in Python list or set for this problem*
+
 (Hint: You might try importing a data structure you built during the week)
 
 #### Task 3. Analyze Some Runtimes