step 1: get the translation texts

php bin/magento i18n:collect-phrases --output=zh_Hans_CN.csv --magento .

Step 2: on root folder there must be translation file of this name

Step 3: Create folders

mkdir app/i18n
mkdir app/i18n/devidiotz/
mkdir app/i18n/devidiotz/zh_Hans_CN/

Step 4 :Create the file composer.json with the following contents:

{
 "name": "test/nl_nl",
   "description": "Chinese Language",
   "version": "100.0.1",
   "license": [
     "OSL-3.0",
     "AFL-3.0"
   ],
   "require": {
     "magento/framework": "100.0.*"
   },
   "type": "magento2-language",
   "autoload": {
     "files": [
       "registration.php"
     ]
   }
   ,"extra": {"map": "*", "devidiotz/zh_Hans_CN"}
 }

Stpe 5 : Create the file language.xml with the following contents:

<?xml version="1.0"?>
<language xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:App/Language/package.xsd">
  zh_Hans_CN
  <vendor>devidiotz</vendor>
  <package>zh_hans_cn</package>
</language>

Step 6: Create the file registration.php with the following content:

<?php
 /**
  * Copyright © 2015 Magento. All rights reserved.
  * See COPYING.txt for license details.
  */  
 \Magento\Framework\Component\ComponentRegistrar::register(
     \Magento\Framework\Component\ComponentRegistrar::LANGUAGE,
     'devidiotz_zh_hans_cn',
     __DIR__
 );

Step 7: deploy setup

php bin/magento setup:static-content:deploy
php bin/magento setup:static-content:deploy nl_NL
php bin/magento indexer:reindex
php bin/magento cache:clean
php bin/magento cache:flush