fix: incorrect problem number (#742)

Author: anmol-fzr

tutorials/basic-topics/sorting/introduction.md

@@ -58,6 +58,6 @@ sort(a.begin(), a.end(), [&](const array<int, 3>& x, const array<int, 3>& y) {
 });
 ```
 
-export const suggestedProblems = [ { "problemName": "0921 - Sort an Array", "difficulty": "Medium", "leetCodeLink": "https://leetcode.com/problems/sort-an-array/", "solutionLink": "../../solutions/0900-0999/sort-an-array-medium" }, ]
+export const suggestedProblems = [ { "problemName": "0912 - Sort an Array", "difficulty": "Medium", "leetCodeLink": "https://leetcode.com/problems/sort-an-array/", "solutionLink": "../../solutions/0900-0999/sort-an-array-medium" }, ]
 
 <Table title="Suggested Problems" data={suggestedProblems} />