docs: update README.md

Author: jonssonyan

README.md

@@ -145,7 +145,7 @@ rm -rf /h-ui
 ## Default Installation Information
 
 - Panel Port: 8081
-- Username/Password: sysadmin
+- Username/Password: Random 6 characters
 
 ## System Upgrade
 

README_ZH.md

@@ -145,7 +145,7 @@ rm -rf /h-ui
 ## 默认安装信息
 
 - 面板端口: 8081
-- 用户名/密码: sysadmin
+- 用户名/密码: 随机6位字符
 
 ## 系统升级
 

docs/FAQ.md

@@ -20,6 +20,12 @@ chmod +x ./h-ui
   ./h-ui -p [port]
   ```
 
+- Reset sysadmin username and password
+
+  ```bash
+  ./h-ui reset
+  ```
+
 ## Meaning of folders in project
 
 - bin: Hysteria2 executable and configuration files

docs/FAQ_ZH.md

@@ -20,6 +20,13 @@ chmod +x ./h-ui
   ./h-ui -p [端口]
   ```
 
+
+- 重设系统管理员用户名和密码
+
+  ```bash
+  ./h-ui reset
+  ```
+
 ## 项目工程中文件夹的含义
 
 - bin: Hysteria2 的可执行文件和配置文件