README: Explain how to get a byte string from a buffer

Closes mathiasbynens/windows-1252#3. Thanks to @Simsso!

README.md

@@ -104,6 +104,8 @@ var text = iso88597.decode(encodedData, {
 // instead of replacing it with U+FFFD in the output, an error is thrown.
 ```
 
+For decoding a buffer (e.g. from `fs.readFile`) use `buffer.toString('binary')` to get the byte string which `decode` takes.
+
 ## Support
 
 _iso-8859-7_ is designed to work in at least Node.js v0.10.0, io.js v1.0.0, Narwhal 0.3.2, RingoJS 0.8-0.11, PhantomJS 1.9.0, Rhino 1.7RC4, as well as old and modern versions of Chrome, Firefox, Safari, Opera, Edge, and Internet Explorer.

data/index.txt

@@ -1,22 +1,19 @@
 # Any copyright is dedicated to the Public Domain.
-# https://creativecommons.org/publicdomain/zero/1.0/
+# http://creativecommons.org/publicdomain/zero/1.0/
 #
-# For details on index index-iso-8859-7.txt see the Encoding Standard
+# For details on index-iso-8859-7.txt see the Encoding Standard
 # https://encoding.spec.whatwg.org/
-#
-# Identifier: f53d8aeba36314ef950eef02ffcf11dff540638ce27dfe7a86b6ccc6875afb24
-# Date: 2016-01-20
 
-  0	0x0080	€ (<control>)
-  1	0x0081	 (<control>)
-  2	0x0082	‚ (<control>)
-  3	0x0083	ƒ (<control>)
-  4	0x0084	„ (<control>)
-  5	0x0085	… (<control>)
-  6	0x0086	† (<control>)
-  7	0x0087	‡ (<control>)
-  8	0x0088	ˆ (<control>)
-  9	0x0089	‰ (<control>)
+	0	0x0080	€ (<control>)
+	1	0x0081	 (<control>)
+	2	0x0082	‚ (<control>)
+	3	0x0083	ƒ (<control>)
+	4	0x0084	„ (<control>)
+	5	0x0085	… (<control>)
+	6	0x0086	† (<control>)
+	7	0x0087	‡ (<control>)
+	8	0x0088	ˆ (<control>)
+	9	0x0089	‰ (<control>)
  10	0x008A	Š (<control>)
  11	0x008B	‹ (<control>)
  12	0x008C	Π(<control>)