Fix in documentation

[yuravake]

Small fix in documentation :
"And the title for each row:
func pickerView(pickerView: PickerView, titleForRow row: Int, index: Int) -> String {
let item = itemsThatYouWantToPresent[row]
return item.text
} "
But we need to use
let item = itemsThatYouWantToPresent[index], not row. It is correct in Example project but not in documentation.

[filipealva]

Hello

Well observed! Thank you so much for reporting.

Solved in: #13