docs: update documentation for automated package updates workflow

AGENTS.md

@@ -21,7 +21,8 @@ Personal Nix flake: custom packages, overlays, NixOS/Home Manager modules, dev s
 ├── shells/                # Dev environments (default, python, devops)
 ├── overlays/mods/         # Package modifications (n8n version bump)
 ├── templates/             # Boilerplate for new packages/modules
-└── examples/              # Usage examples
+├── examples/              # Usage examples
+└── .gitea/workflows/     # CI/CD workflows (nix-update automation)
 ```
 
 ## WHERE TO LOOK
@@ -34,6 +35,7 @@ Personal Nix flake: custom packages, overlays, NixOS/Home Manager modules, dev s
 | Override nixpkgs pkg | `overlays/mods/<name>.nix`         | Import in `overlays/mods/default.nix` |
 | Add dev shell        | `shells/<name>.nix`                | Register in `shells/default.nix`      |
 | Use port management  | `config.m3ta.ports.get "service"`  | Host-specific via `hostOverrides`     |
+| CI/CD workflows      | `.gitea/workflows/<name>.yml`      | Automated package updates (nix-update) |
 
 ## CONVENTIONS
 
@@ -146,6 +148,7 @@ Types: `feat`, `fix`, `docs`, `style`, `refactor`, `chore`
 - **Ports module**: Different for NixOS vs HM (HM adds `generateEnvVars` option)
 - **Overlays**: `modifications` overlay uses `{prev}:` pattern, not `{final, prev}:`
 - **Dev shell tools**: `statix`, `deadnix` only available inside `nix develop`
+- **Automated package updates**: Packages are automatically updated weekly via Gitea Actions using `nix-update`. Review PRs from the automation before merging. For urgent updates, manually run the workflow or update manually.
 
 ## Issue Tracking