Clarify the use of the --version option for import-debian-package

This option is not commonly used for the Apertis maintenance, but
very useful in some specific cases. Add a concrete example of how
to use it.

Signed-off-by: Dylan Aïssi <dylan.aissi@collabora.com>

content/guides/component_guide.md

@@ -87,10 +87,6 @@ have access to the Apertis Gitlab server, see
 
       $ import-debian-package --upstream buster --downstream apertis/v2021 --component target --package hello --push-remote
 
-  To fetch a specific version, add the `--version` option:
-
-      $ import-debian-package --upstream buster --downstream apertis/v2021 --component target --package hello --push-remote --version 2.10-2
-
   * The argument to `--component` reflects the repository component it is part
     of (for instance, `target`); it will be stored in
     `debian/apertis/component`.
@@ -115,6 +111,18 @@ have access to the Apertis Gitlab server, see
   branches based on the freshly imported Debian package.
   {{% /notice %}}
 
+Occasionally, we may need to import a specific version not available anymore
+in the official Debian archive. By passing the `--version` option to
+`import-debian-package`, it will fetch the given version from the official
+Debian snapshot archive: [snapshot.debian.org](https://snapshot.debian.org/).
+
+Let's take the example of `pipewire` version `0.3.10-1`. This version is not
+available anymore in the main archive since Debian 10 provides `0.2.5-1`
+whereas Debian 11 provides `0.3.19-4`. Thus, we can import this version
+by passing `--version 0.3.10-1`:
+
+      $ import-debian-package --upstream snapshot --downstream apertis/v2021 --component target --package pipewire --version 0.3.10-1
+
 ## Adding New Packages from Upstream Sources
 
 There are likely to be instances where it is desirable to import the latest