add link to ru readme

Author: Blueberryy

README_cn.md

@@ -11,6 +11,7 @@
 ---
 <p align="center">
   <a href="README.md">English</a> -
+  <a href="README_ru.md">Русский</a> -
   <a href="README_cn.md">简体中文</a>
 </p>
 &nbsp;
@@ -92,4 +93,4 @@ LZX|压缩率最高，解压速度最慢|适合用于存档文件、备份数据
  请考虑在 Ko-Fi 上打赏一下 :)
 
  <p align="left"><a href='https://ko-fi.com/iridiumio' target='_blank'><img height='42' style='border:0px;height:42px;' src='https://cdn.ko-fi.com/cdn/kofi3.png?v=3' border='0' alt='Buy Me a Coffee at ko-fi.com' /></a></p>
-  
+