Update README.md

Author: josemoracard

exercises/26-two-dimensional-array/README.md

@@ -2,7 +2,7 @@
 
 ## 📝 Instructions:
 
-1. Write a function `two_dimensional_list`, that takes 2 digits (x, y) as input and generates a 2-dimensional list or matrix.
+1. Write a function `two_dimensional_list()`, that takes 2 digits (x, y) as input and generates a 2-dimensional list or matrix.
 
 2. The element value in the `i` row and `j` column of the list should be `i*j` (their index values).