Find a place for reference documentation in Serving a Nix store via SSH

[fricklerhandwerk]

Problem

Serving a Nix store via SSH is a how-to guide that should be removed from the reference manual, see #7769.

Proposal

It's not entirely clear where the still interesting reference-style information and examples that don't appear anywhere else should go instead. There currently seems to be no place where the different URL syntaxes for substituters are documented.

Options:

• nix-copy-closure
• substituters

Move the information, remove the page.

Important
add a redirect on nixos.org, otherwise existing links will break

Priorities

Add 👍 to issues you find important.

[nixos-discourse]

This issue has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/2023-03-21-documentation-team-meeting-notes-34/26619/1