fix: add the image prefix to offline

documents/docs/02-guide/01-install.md

@@ -67,6 +67,7 @@ style={{ width: '100%', height: '350px' }}
    MGT_PORT=9443
    POSTGRES_PASSWORD=$(LC_ALL=C tr -dc A-Za-z0-9 </dev/urandom | head -c 32)
    SUBNET_PREFIX=172.22.222
+   IMAGE_PREFIX=chaitin
    EOF
    ```
 

documents/docs/02-guide/06-upgrade.md

@@ -51,7 +51,7 @@ grep "SAFELINE_DIR" ".env" > /dev/null || echo "SAFELINE_DIR=$(pwd)" >> ".env"
 grep "IMAGE_TAG" ".env" > /dev/null || echo "IMAGE_TAG=latest" >> ".env"
 grep "MGT_PORT" ".env" > /dev/null || echo "MGT_PORT=9443" >> ".env"
 grep "POSTGRES_PASSWORD" ".env" > /dev/null || echo "POSTGRES_PASSWORD=$(LC_ALL=C tr -dc A-Za-z0-9 </dev/urandom | head -c 32)" >> ".env"
-grep "SUBNET_PREFIX" ".env" > /dev/null || echo "SUBNET_PREFIX=172.22.222" >> ".env"
+grep "IMAGE_PREFIX" ".env" >/dev/null || echo "IMAGE_PREFIX=chaitin" >>".env"
 ```
 
 下载 [雷池社区版镜像包](https://demo.waf-ce.chaitin.cn/image.tar.gz) 并传输到需要安装雷池的服务器上，执行以下命令加载镜像