Admin 整体架构与安装步骤

三种安装方式均有问题：
安装方式一：Dubboctl 安装：git clone https://github.com/apache/dubbo-admin.git拉取不下来；
安装方式二：Helm 安装，请说清楚是helm2还是3，我用的heml3,在执行helm repo add 时，报该命令需要两个参数的异常；
安装方式三：VM 安装，curl installer.sh时，报：
sh: line 1: syntax error near unexpected token `newline'
sh: line 1: `'

到底如何安装，请文档里写清楚

Review the Dubbo Admin documentation sections for Dubboctl, Helm, and VM installation, then reproduce the reported clone, helm repo add, and installer.sh failures. Confirm the supported Helm version and valid installation commands for each method; the documentation is done when all three procedures are unambiguous and executable.

Written by the indexing model from the issue text.