Chapter 4 exercise order

[amy-datacamp]

@yashasroy @richierocks In Chapter 4 "Sorting multiple columns" ex 5 (https://campus.datacamp.com/courses/intro-to-sql-for-data-science/sorting-grouping-and-joins?ex=5), sub-exercises 1 and 4 refer to the people table, while exercise 2 and 3 refer to the films table. Since this is a bulleted exercise, the exercises could be moved to decrease the amount of editing the student makes to the code.

Changing the exercise order to reduce the amount of editing also addresses the comment raised by the student below, since the exercises are different, which would be more clear if the order were changed.