Add Proxmox helper scripts link to installation guide

[andypiper]

No description provided.

[fisharebest]

I notice that your install script makes a curl request to the setup wizard to create the admin user.

There is a simpler alternative. webtrees has a CLI interface, which allows you to create/update the config.ini.php file, create/edit users and trees.

So you could create/update the config file and create/update the admin user using local CLI commands.

For a list of commands, run php index.php list.

These scripts were designed to support automated deployment such as these. If there's anything missing/broken, please open an issue.