doc: fix line length and wording

Author: ramsgoli

doc/api/util.md

@@ -554,8 +554,8 @@ will return its value, see [Custom promisified functions][].
 `promisify()` assumes that `original` is a function taking a callback as its
 final argument in all cases. If `original` is not a function, `promisify()` 
 will throw an error. If `original` is a function but its last argument is not a 
-Node.js style callback, it will be still be passed a Node.js style callback as its last
-argument.
+Node.js style callback, it will still be passed a Node.js style callback 
+as its last argument.
 
 ### Custom promisified functions