Update README

Author: umbri

README.md

@@ -36,7 +36,7 @@ $data = msgpack_unpack($msg);
 ```php
 <?php
 $data = array(0 => 1, 1 => 2, 2 => 3);
-$packer = new \MessagePack(false);
+$packer = new \MessagePack(false); //same as $packer->setOption(\MessagePack::OPT_PHPONLY, false);
 $packed = $packer->pack($data);
 
 $unpacker = new \MessagePackUnpacker(false);
@@ -53,7 +53,7 @@ $unpacker->reset();
 $data1 = array(0 => 1, 1 => 2, 2 => 3);
 $data2 = array("a" => 1, "b" => 2, "c" => 3);
 
-$packer = new \MessagePack(false);
+$packer = new \MessagePack(false); //same as $packer->setOption(\MessagePack::OPT_PHPONLY, false);
 $packed1 = $packer->pack($data1);
 $packed2 = $packer->pack($data2);