Update README_CN.md

Author: hejianxin79

README_CN.md

@@ -56,7 +56,7 @@ MODBUS: "None" or "RML"
 
   L20: ["拇指根部", "食指根部", "中指根部", "无名指根部","小指根部","拇指侧摆","食指侧摆","中指侧摆","无名指侧摆","小指侧摆","拇指横摆","预留","预留","预留","预留","拇指尖部","食指末端","中指末端","无名指末端","小指末端"]
 
-  L25: ["大拇指根部", "食指根部", "中指根部","无名指根部","小拇指根部","大拇指侧摆","食指侧摆","中指侧摆","无名指侧摆","小拇指侧摆","大拇指横滚","预留","预留","预留","预留","大拇指中部","预留","预留","预留","预留","大拇指指尖","食指指尖","中指指尖","无名指指尖","小拇指指尖"]
+  L21: ["大拇指根部", "食指根部", "中指根部","无名指根部","小拇指根部","大拇指侧摆","食指侧摆","中指侧摆","无名指侧摆","小拇指侧摆","大拇指横滚","预留","预留","预留","预留","大拇指中部","预留","预留","预留","预留","大拇指指尖","食指指尖","中指指尖","无名指指尖","小拇指指尖"]
 
   L25: ["大拇指根部", "食指根部", "中指根部","无名指根部","小拇指根部","大拇指侧摆","食指侧摆","中指侧摆","无名指侧摆","小拇指侧摆","大拇指横滚","预留","预留","预留","预留","大拇指中部","食指中部","中指中部","无名指中部","小拇指中部","大拇指指尖","食指指尖","中指指尖","无名指指尖","小拇指指尖"]