fix: making the grade docs fix (#953)

Author: Sencudra

exercises/concept/making-the-grade/.docs/hints.md

@@ -24,7 +24,10 @@ Also being familiar with the following can help with completing the tasks:
 
 ## 3. Calculating Letter Grades
 
-- These are _lower thresholds_. The _lower threshold_ for a "D" is a score of **41**, since an "F" is **<= 40**.
+- The score needed to avoid failing is always 41, since an "F" is **<= 40**. The remaining score range, from 41 to the highest score, should be divided into four equal intervals, one for each letter grade.
+- Subtract 40 from the highest score to get the total range of scores that qualify for letter grades (A to D).
+- Divide this total range by 4 to get the size of each grade interval.
+- Add this interval size to 40 repeatedly to calculate the lower bounds for each letter grade.
 - `static_cast<int>` without parameters should round off increments nicely.
 - You are expected to return an array, not a vector.
 

exercises/concept/making-the-grade/.docs/instructions.md

@@ -74,15 +74,6 @@ letter_grades(88);
 // => {41, 53, 65, 77}
 ```
 
-### How to calculate the intervals
-
-The score needed to avoid failing is always 41.
-The remaining score range, from 41 to the highest score, should be divided into four equal intervals, one for each letter grade.
-
-- Subtract 40 from the highest score to get the total range of scores that qualify for letter grades (A to D).
-- Divide this total range by 4 to get the size of each grade interval.
-- Add this interval size to 40 repeatedly to calculate the lower bounds for each letter grade.
-
 ## 4. Matching Names to Scores
 
 You have exam scores in descending order, and the respective student names (sorted in the order of their exam scores).