4_permutations: Fix typo in README (#637)

Author: SuperScuffedDev

computer_science/recursion/4_permutations/README.md

@@ -1,6 +1,6 @@
 # Exercise 4 - permutations
 
-Write a function that takes in an empty array or an input array of an consecutive positive integers, starting at 1, and returns an array of all possible permutations of the original array
+Write a function that takes in an empty array or an input array of consecutive positive integers, starting at 1, and returns an array of all possible permutations of the original array.
 
 The integers will not repeat.