style: Reformat reference

Author: CaedenPH

matrix/count_negative_numbers_in_sorted_matrix.py

@@ -2,7 +2,7 @@
 Given an `m x n` matrix grid which is sorted in non-increasing order
 both row-wise and column-wise, return the number of negative numbers in grid.
 
-> https://leetcode.com/problems/count-negative-numbers-in-a-sorted-matrix
+Leetcode reference: https://leetcode.com/problems/count-negative-numbers-in-a-sorted-matrix
 """