docs: cleanup the explanation paragraphs at the start of each exercise.

exercises/quiz1.rs

@@ -1,14 +1,17 @@
 // quiz1.rs
+//
 // This is a quiz for the following sections:
 // - Variables
 // - Functions
 // - If
-
+//
 // Mary is buying apples. The price of an apple is calculated as follows:
 // - An apple costs 2 rustbucks.
 // - If Mary buys more than 40 apples, each apple only costs 1 rustbuck!
-// Write a function that calculates the price of an order of apples given
-// the quantity bought. No hints this time!
+// Write a function that calculates the price of an order of apples given the
+// quantity bought. No hints this time!
+//
+// No hints this time ;)
 
 // I AM NOT DONE