Add documentation about how to configure and install bureautix

[shiipou]

I've compiled my ISO to test bureautix on my desktop, and here what I found we have to do :

1. Forking cloud-gouv/bureautix (and optionally cloud-gouv/securix when the hardware SKU isn't yet supported)
2. Retrieve the serial number and hardware SKU from the machine with (dmidecode -s system-serial-number)
3. Adding inventory/machines/<SERIAL>.nix and inventory/users/<username>.nix with complete Nix examples
4. Customising common modules (admins, U2F keys, browser, tools, etc.) with the pamu2fcfg command to generate Yubikey entries
5. Compile the ISO with nix-build -A terminals.<SERIAL> and flash it to an USB stick.
6. Run autoinstall-terminal command to start the install process.
7. Applying the config post-boot via root by cloning the repo, nix-build, then switch-to-configuration switch

Can you please details the process in the README.md or with an INSTALL.md, so we can try it more easily. (Via ISO and via netboot)
Also explaining how to add a new package, and applying it after boot, and the automatic update process.

Thanks a lot for your help.

[FlorianT-FR]

Hello,
Adding a documentation is a good idea. However, I noticed that Sécurix has no support nor documentation, that can explain why Bureautix don't have one.

I tested your instructions on a Qemu VM and they're good except about these points :

• dmidecode and pamu2f aren't installed by default on the NixOS installation media, so I needed to run these commands : nix-env -iA nixos.dmidecode and nix-env -iA nixos.pam_u2f
• The hardware SKU and serial number aren't defined when running on a VM by default (can someone help me about this please?)
• I hadn't enough space to build the ISO on the live environment

You should make a pull request adding an INSTALL.md with these instructions.

Thanks for your help.

PS : I can help if someone needs to translate something in French

[T2an]

I've been working on an INSTALL.md (inventory to first boot, tested on a lab VM). Didn't cover netboot yet.

The npins still point to Securix from October 2025, a lot has landed since then and the examples barely cover it (I had to bump npins to get it building). Might be worth a separate issue to track updating common/ alongside the doc work.

I'll open a PR for the install guide soon.