Pull request: Updating Freelancer Rates exercise instructions

I started solving the C++ exercises recently and noticed that some of them are missing information. One of them is Freelancer Rates where the most obvious way of completing the exercise for parts 3 and 4 use the floor() and ceil() functions from the library, but it’s not mentioned in there, nor is it in the concepts connected to the exercise. Would this be okay to make a pull request for?