chore(docs): add systemd steps to Debian upgrade

Part-of: <https://dev.funkwhale.audio/funkwhale/funkwhale/-/merge_requests/2423>

changes/changelog.d/1966.doc

@@ -0,0 +1 @@
+Add systemd update instructions to Debian upgrade instructions (#1966)

docs/administrator/upgrade/debian.md

@@ -6,20 +6,20 @@ If you installed Funkwhale following the [Debian guide](../installation/debian.m
 
 1. Stop the Funkwhale services.
 
-   ```{code-block} sh
-   sudo systemctl stop funkwhale.target
+   ```console
+   # systemctl stop funkwhale.target
    ```
 
 2. Navigate to your Funkwhale directory.
 
-   ```{code-block} sh
-   cd /srv/funkwhale
+   ```console
+   # cd /srv/funkwhale
    ```
 
 3. Remove the old files.
 
-   ```{code-block} sh
-   sudo rm -Rf api/* front/* venv
+   ```console
+   # rm -Rf api/* front/* venv
    ```
 
 ## Download Funkwhale
@@ -33,6 +33,17 @@ If you installed Funkwhale following the [Debian guide](../installation/debian.m
 2. Follow the [Download Funkwhale](../installation/debian.md#3-download-funkwhale) instructions in the installation guide.
 3. Follow the [Install the Funkwhale API](../installation/debian.md#4-install-the-funkwhale-api) instructions in the installation guide.
 
+## Upgrade your systemd unit files
+
+To make sure you receive any updates made to unit files, download the latest versions from the repo.
+
+```console
+# curl -L -o "/etc/systemd/system/funkwhale.target" "https://dev.funkwhale.audio/funkwhale/funkwhale/raw/$FUNKWHALE_VERSION/deploy/funkwhale.target"
+# curl -L -o "/etc/systemd/system/funkwhale-server.service" "https://dev.funkwhale.audio/funkwhale/funkwhale/raw/$FUNKWHALE_VERSION/deploy/funkwhale-server.service"
+# curl -L -o "/etc/systemd/system/funkwhale-worker.service" "https://dev.funkwhale.audio/funkwhale/funkwhale/raw/$FUNKWHALE_VERSION/deploy/funkwhale-worker.service"
+# curl -L -o "/etc/systemd/system/funkwhale-beat.service" "https://dev.funkwhale.audio/funkwhale/funkwhale/raw/$FUNKWHALE_VERSION/deploy/funkwhale-beat.service"
+```
+
 ## Update your reverse proxy configuration
 
 To ensure your reverse proxy is up-to-date with changes, you should regenerate your Nginx configuration with each upgrade. To do this:
@@ -54,26 +65,26 @@ Once you have downloaded the new files, you can update your Funkwhale instance.
 
 1. Install or upgrade all OS dependencies using the dependencies script.
 
-   ```{code-block} sh
-   sudo api/install_os_dependencies.sh install
+   ```console
+   # api/install_os_dependencies.sh install
    ```
 
 2. Collect the new static files to serve.
 
-   ```{code-block} sh
-   sudo venv/bin/funkwhale-manage collectstatic --no-input
+   ```console
+   # venv/bin/funkwhale-manage collectstatic --no-input
    ```
 
 3. Apply new database migrations.
 
-   ```{code-block} sh
-   sudo -u funkwhale venv/bin/funkwhale-manage migrate
+   ```console
+   # sudo -u funkwhale venv/bin/funkwhale-manage migrate
    ```
 
 4. Restart the Funkwhale services.
 
-   ```{code-block} sh
-   sudo systemctl start funkwhale.target
+   ```console
+   # systemctl start funkwhale.target
    ```
 
 That's it! You've updated your Funkwhale pod. You should now see the new version running in your web browser.