add arch package doc (#791)

This is the documentation for PR https://codeberg.org/forgejo/forgejo/pulls/4785.

Reviewed-on: https://codeberg.org/forgejo/docs/pulls/791
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Reviewed-by: Robert Wolff <mahlzahn@posteo.de>
Co-authored-by: dragon <explodingfkl@gmail.com>
Co-committed-by: dragon <explodingfkl@gmail.com>

docs/user/packages/arch.md

@@ -0,0 +1,88 @@
+---
+title: 'Arch Package Registry'
+license: 'Apache-2.0'
+---
+
+Forgejo has a Arch Linux package registry, which can act as a fully working [Arch linux mirror](https://wiki.archlinux.org/title/mirrors) and connected directly in `/etc/pacman.conf`. Forgejo automatically creates pacman database for packages in user/organization space when a new Arch package is uploaded.
+
+## Upload packages
+
+When uploading the package to Forgejo, you have to prepare package file with the `.pkg.tar.zst` extension 。You can use [curl](https://curl.se/) or any other HTTP client, Forgejo supports multiple [authentication schemes](https://docs.Forgejo.com/usage/authentication). The upload command will create 3 files: package, signature and desc file for the pacman database (which will be created automatically on request).
+
+The following command will upload arch package and related signature to Forgejo with basic authentification:
+
+```sh
+curl -X PUT \
+  https://{domain}/api/packages/{owner}/arch/{group} \
+  --user your_username:your_token_or_password \
+  --header "Content-Type: application/octet-stream" \
+  --data-binary '@/path/to/package/file/package-1-1-x86_64.pkg.tar.zst'
+```
+
+| Placeholder | Description                                                                                 |
+| ----------- | ------------------------------------------------------------------------------------------- |
+| `owner`     | The owner of the package                                                                    |
+| `group`     | [Repository](https://wiki.archlinux.org/title/Official_repositories), e.g. `os`, `extras` . |
+
+## Install packages
+
+First, you need to update your pacman configuration, adding following lines :
+
+```conf
+[{owner}.{group}.{domain}]
+SigLevel = Required
+Server = https://{domain}/api/packages/{owner}/arch/{group}/{architecture}
+```
+
+You can also copy content from the Forgejo package page.
+
+| Placeholder    | Description                                                                               |
+| -------------- | ----------------------------------------------------------------------------------------- |
+| `owner`        | The owner of the package                                                                  |
+| `group`        | [Repository](https://wiki.archlinux.org/title/Official_repositories), e.g. `os`, `extras` |
+| `architecture` | System architecture, such as `x86_64`, `aarch64`                                          |
+
+Then, Import the server's public key.
+
+```bash
+# Download the public key from the remote server.
+wget -O sign.gpg https://{domain}/api/packages/{owner}/arch/repository.key
+
+# Import the public key for pacman.
+pacman-key --add sign.gpg
+
+# Trust the certificate with the specified email
+pacman-key --lsign-key '{owner}@noreply.{domain}'
+```
+
+| Placeholder | Description                                      |
+| ----------- | ------------------------------------------------ |
+| `domain`    | Your Forgejo domain, such as `code.forgejo.org`. |
+| `owner`     | The owner of the package                         |
+
+Finally, you can run pacman sync command (with -y flag to load connected database file), to install your package:
+
+```sh
+pacman -Sy {package}
+```
+
+## Delete packages
+
+The `DELETE` method will remove specific package version, and all package files related to that version:
+
+```sh
+curl -X DELETE \
+  https://{domain}/api/packages/{owner}/arch/{group}/{package}/{version} \
+  --user your_username:your_token_or_password
+```
+
+| Placeholder | Description                                                                               |
+| ----------- | ----------------------------------------------------------------------------------------- |
+| `owner`     | The owner of the package                                                                  |
+| `group`     | [Repository](https://wiki.archlinux.org/title/Official_repositories), e.g. `os`, `extras` |
+| `package`   | Package name                                                                              |
+| `version`   | Package version                                                                           |
+
+## Clients
+
+Any `pacman` compatible package manager or AUR-helper can be used to install packages from Forgejo ([yay](https://github.com/Jguer/yay), [paru](https://github.com/Morganamilo/paru), [pikaur](https://github.com/actionless/pikaur), [aura](https://github.com/fosskers/aura)). Also, any HTTP client can be used to execute get/push/remove operations ([curl](https://curl.se/), [postman](https://www.postman.com/), [thunder-client](https://www.thunderclient.com/)).

docs/user/packages/index.md

@@ -11,6 +11,7 @@ The following package managers are currently supported:
 | Name                      | Language   | Package client             |
 | ------------------------- | ---------- | -------------------------- |
 | [Alpine](./alpine/)       | -          | `apk`                      |
+| [Arch](./arch/)           | -          | `pacman`                   |
 | [Cargo](./cargo/)         | Rust       | `cargo`                    |
 | [Chef](./chef/)           | -          | `knife`                    |
 | [Composer](./composer/)   | PHP        | `composer`                 |