Fix Buffer type

Closes GH-20.

Reviewed-by: Christian Murphy <christian.murphy.42@gmail.com>
Reviewed-by: Titus Wormer <tituswormer@gmail.com>

Author: remcohaszing

lib/index.js

@@ -7,8 +7,9 @@
  * @typedef {BufferEncoding|{encoding?: null|BufferEncoding, flag?: string}} ReadOptions
  * @typedef {BufferEncoding|{encoding?: null|BufferEncoding, mode: Mode?, flag?: string}} WriteOptions
  *
- * @typedef {string|Uint8Array} Path Path of the file.
- * @typedef {Path|URL|Options|VFile} Compatible Things that can be
+ * @typedef {URL|Value} Path Path of the file.
+ *   Note: `Value` is used here because it’s a smarter `Buffer`
+ * @typedef {Path|Options|VFile} Compatible Things that can be
  *   passed to the function.
  */