Update README.markdown

`sort()` is in place sort. in reveres `sorted()` returns a sorted copy of the original array

Insertion Sort/README.markdown

@@ -114,7 +114,7 @@ insertionSort(list)
 
 Here is how the code works.
 
-1. Make a copy of the array. This is necessary because we cannot modify the contents of the `array` parameter directly. Like Swift's own `sort()`, the `insertionSort()` function will return a sorted *copy* of the original array.
+1. Make a copy of the array. This is necessary because we cannot modify the contents of the `array` parameter directly. Like Swift's own `sorted()`, the `insertionSort()` function will return a sorted *copy* of the original array.
 
 2. There are two loops inside this function. The outer loop looks at each of the elements in the array in turn; this is what picks the top-most number from the pile. The variable `x` is the index of where the sorted portion ends and the pile begins (the position of the `|` bar). Remember, at any given moment the beginning of the array -- from index 0 up to `x` -- is always sorted. The rest, from index `x` until the last element, is the unsorted pile.