Fix Mooophy#538

ch09/README.md

@@ -29,7 +29,7 @@ two iterators, `begin` and `end`:
 >Write a function that takes a pair of iterators to a vector<int> and an int value. Look for that value in the range and return a bool indicating whether it was found.
 
 ```cpp
-auto contains(vector<int>::const_iterator first, vector<int>::const_iterator last, int value)
+bool contains(vector<int>::const_iterator first, vector<int>::const_iterator last, int value)
 {
     for(; first != last; ++first)
         if(*first == value) return true;