shopping_mall function name typo

subjects/shopping_mall/README.md

@@ -8,14 +8,14 @@ Using the `mall` module provided create the following **functions** to help run
 - `highest_paid_employees`: receives a `mall::Mall` and returns a vector containing the `Employee`(s) with the highest salaries;
 - `nbr_of_employees`: receives a `mall::Mall` and returns the number of employees and securities, as a `usize`, in that mall.
 - `fire_old_securities`: receives a `mall::Mall` and removes from the `mall::Mall.securities` all securities who are 50 years old or older.
-- `check_securities`: receives a `mall::Mall` and a vector of `Security` and, if there is not at least 1 security for every 200 square meters of floor size, a security should be added to the `mall::Mall.securities`
+- `check_for_securities`: receives a `mall::Mall` and a vector of `Security` and, if there is not at least 1 security for every 200 square meters of floor size, a security should be added to the `mall::Mall.securities`
 - `cut_or_raise`: receives a `mall::Mall` and raises or cuts, the salary of every employee in the mall by 10%, if the employee works for more than 10 hours
 
 ### Expected Function
 
 #### For this exercise the signature of the function has to be found out.
 
-### mall.rs
+### mall.rs
 
 ```rust
 #[derive(Debug, Clone, PartialEq)]