docs(datasource/deb): document steps for Artifactory (#31110)

Co-authored-by: HonkingGoose <34918129+HonkingGoose@users.noreply.github.com>

lib/modules/datasource/deb/readme.md

-The Debian datasource enables Renovate to update packages from Debian repositories. It is ideal for projects that depend on Debian-based systems or distributions. You will need to combine Debian datasource with [regex managers](../../manager/regex/index.md) to update dependencies.
+Renovate uses the Debian datasource to update packages from Debian repositories.
+The `debian` datasource is meant for projects that:
 
-**Registry URL**
-To use a Debian repository with the datasource, you need a properly formatted URL with specific query parameters:
+- depend on Debian-based systems, or
+- depend on Debian-based distributions, like Ubuntu
+
+By default, Renovate does not detect Debian dependencies.
+For Renovate to update dependencies, you must combine the Debian datasource with [regex managers](../../manager/regex/index.md).
+
+## Set URL when using a Debian repository
+
+To use a Debian repository with the datasource, you must set a properly formatted URL with specific query parameters as `registryUrl`:
 
 - `components`: Comma-separated list of repository components (e.g., `main,contrib,non-free`).
 - `binaryArch`: Architecture of the binary packages (e.g., `amd64`,`all`).
@@ -9,6 +17,11 @@ To use a Debian repository with the datasource, you need a properly formatted UR
   - `suite`: A rolling release alias like `stable`.
   - `release`: A fixed release name such as `bullseye` or `buster`.
 
+<!-- prettier-ignore -->
+!!! note
+  These parameters are used to give Renovate context and are not directly used to call the repository.
+  Therefore, the `registryUrl` has not to be a valid URL for a repository.
+
 **Example**:
 
 ```
@@ -17,7 +30,7 @@ https://deb.debian.org/debian?suite=stable&components=main,contrib,non-free&bina
 
 This URL points to the `stable` suite of the Debian repository for `amd64` architecture, including `main`, `contrib`, and `non-free` components.
 
-**Usage Example**
+## Usage Example
 
 Say you're using apt packages in a Dockerfile and want to update them.
 With the debian datasource you can "pin" each dependency, and get automatic updates.
@@ -32,8 +45,9 @@ First you would set a custom manager in your `renovate.json` file for `Dockerfil
       "customType": "regex",
       "fileMatch": ["^Dockerfile$"],
       "matchStrings": [
-        "#\\s*renovate:\\s*?depName=(?<depName>.*?)?\\sENV .*?_VERSION=\"(?<currentValue>.*)\"\\s"
+        "#\\s*renovate:\\s*?(release=(?<release>.*?))?\\s*depName=(?<depName>.*?)?\\sENV .*?_VERSION=\"(?<currentValue>.*)\""
       ],
+      "registryUrlTemplate": "https://deb.debian.org/debian?{{#if release }}release={{release}}{{else}}suite=stable{{/if}}&components=main,contrib,non-free&binaryArch=amd64",
       "datasourceTemplate": "deb"
     }
   ]
@@ -45,7 +59,7 @@ Then you would put comments in your Dockerfile, to tell Renovate where to find t
 ```dockerfile
 FROM debian:bullseye
 
-# renovate: depName=gcc-11
+# renovate: release=bullseye depName=gcc-11
 ENV GCC_VERSION="11.2.0-19"
 
 RUN apt-get update && \
@@ -55,3 +69,57 @@ RUN apt-get update && \
 ```
 
 When the apt package for `gcc` is updated, Renovate updates the environment variable.
+
+```json title="Override deb registryUrl with a packageRules entry"
+{
+  "packageRules": [
+    {
+      "matchDatasources": ["deb"],
+      "matchPackageNames": ["gcc-11"],
+      "registryUrls": [
+        "https://deb.debian.org/debian?suite=stable&components=main,contrib,non-free&binaryArch=amd64"
+      ]
+    }
+  ]
+}
+```
+
+## Artifactory
+
+The Debian datasource can be used with Artifactory.
+
+### Supported repository types
+
+The `debian` datasource supports these repository types:
+
+- virtual
+- local
+- remote
+
+### Set a `registryUrl`
+
+To use Artifactory, first configure the `deb` datasource by setting the `registryUrl`.
+
+```title="Example of valid registryUrl format"
+https://<host>:<port>/artifactory/<repository-slug>?release=<release>&components=<components>&binaryArch=<binaryArch>
+https://artifactory.example.com:443/artifactory/debian?release=bookworm&components=main,contrib,non-free&binaryArch=amd64
+```
+
+### Authenticating to Artifactory
+
+If Artifactory asks for authentication, you must set up a host rule.
+First, generate a password for Renovate with Artifactory's "Set Me Up" feature.
+Then, add the following configuration:
+
+```json title="Example Artifactory host rule configuration, with username and password"
+{
+  "hostRules": [
+    {
+      "hostType": "deb",
+      "matchHost": "https://artifactory.example.com:443/artifactory/debian",
+      "username": "myuser",
+      "password": "< the generated password >"
+    }
+  ]
+}
+```