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

exercises/iterators/iterators5.rs

@@ -1,4 +1,5 @@
 // iterators5.rs
+//
 // Let's define a simple model to track Rustlings exercise progress. Progress
 // will be modelled using a hash map. The name of the exercise is the key and
 // the progress is the value. Two counting functions were created to count the
@@ -6,7 +7,9 @@
 // functionality using iterators. Try not to use imperative loops (for, while).
 // Only the two iterator methods (count_iterator and count_collection_iterator)
 // need to be modified.
-// Execute `rustlings hint iterators5` or use the `hint` watch subcommand for a hint.
+//
+// Execute `rustlings hint iterators5` or use the `hint` watch subcommand for a
+// hint.
 
 // I AM NOT DONE