Update 成为主网验证节点.md

Author: qiusese

docs/成为主网验证节点.md

@@ -326,6 +326,21 @@ chmod +x mtool_install.sh && ./mtool_install.sh
 
 After installation is complete, you need to <font color='red'>restart the session window (do not restart the server, close the session window or SSH tool to reopen the window)</font> for the newly added environment variables to take effect.
 
+## Modifying the Chain ID in the Configuration File
+There are differences in the use of environment variables for the PlatON MTool directory between Windows and Ubuntu:
+
+- Windows
+
+  - Path: mtool\current\config
+
+  - Change chainId=100 to chainId=210425
+
+- Ubuntu
+
+  - Path: /platon_mtool/config.properties
+
+  - Change chainId=100 to chainId=210425
+
 ### Configure PlatON MTool
 
 #### Generate wallet