docs: mention --username option in uv/pip FAQ password reset entry

docs/en/faq.md

@@ -48,6 +48,8 @@ Run the following in the AstrBot working directory (the one initialized with `as
 astrbot password
 ```
 
+To also change the username, add the `--username` option: `astrbot password --username <new-username>`.
+
 Then restart AstrBot for the change to take effect. You can also reset the password at startup and print the new one in the logs: `astrbot run --reset-password`.
 
 #### Other Deployment Methods

docs/zh/faq.md

@@ -49,6 +49,8 @@ sudo docker restart astrbot # 修改后需要重启容器才能生效
 astrbot password
 ```
 
+如需同时修改用户名，可以加 `--username` 参数：`astrbot password --username <新用户名>`。
+
 然后重启 AstrBot 生效。也可以在启动时重置并在日志中打印新密码：`astrbot run --reset-password`。
 
 #### 其他部署方式