chore: Clarify comment in exercises/test1.rs

closes #194

The author of issue #194 suggests that the wording of the comment is at
least ambiguous about the desired results. I believe this change more
clearly describes the expectation of the exercise.

Author: ssweeny

exercises/test1.rs

@@ -4,7 +4,7 @@
 // - Functions
 
 // Mary is buying apples. One apple usually costs 2 dollars, but if you buy
-// more than 40 at once, each apple only costs 1! Write a function that calculates
+// 40 or more at once, each apple only costs 1! Write a function that calculates
 // the price of an order of apples given the order amount. No hints this time!
 
 // Put your function here!