Specify thatfib(48) needn't get a correct treatment

* Closes #340

fibonacci/README.md

@@ -5,6 +5,7 @@ This program should benchmark a function computing `fibonacci(n)` using naïve r
 * For the non-base cases the code should do two recursive calls.
 * The code should be free of any hints to the compiler to memoize, use tail recursion,
   iterative methods, or any avoidance of the naïve recursion.
+* The program need not handle `n > 47` in a correct way. 
 
 If some compiler finds ways to avoid recursive calls without any hints, than that is a result. We are in some sense testing compilers here, after all.