add systemd guide

Signed-off-by: Tealk <tealk@rollenspiel.monster>

examples/systemd.md

@@ -0,0 +1,90 @@
+1. Navigate to the directory `/opt`:
+    ```bash
+    cd /opt
+    ```
+
+2. Clone the FediFetcher repository from GitHub:
+    ```bash
+    git clone https://github.com/nanos/FediFetcher.git
+    ```
+
+3. Create a Python Virtual Environment named `fedifetcher`:
+    ```bash
+    python3 -m venv fedifetcher
+    ```
+
+4. Change to the FediFetcher directory:
+    ```bash
+    cd FediFetcher
+    ```
+
+5. Activate the virtual environment:
+    ```bash
+    source /opt/fedifetcher/bin/activate
+    ```
+
+6. Install the required Python packages from the `requirements.txt` file:
+    ```bash
+    pip install -r requirements.txt
+    ```
+
+7. Deactivate the virtual environment:
+    ```bash
+    deactivate
+    ```
+
+8. Configure FediFetcher according to the instructions provided at: [Configuration Options](https://github.com/nanos/FediFetcher?tab=readme-ov-file#configuration-options).
+
+9. Run FediFetcher for the first time:
+    ```bash
+    /opt/fedifetcher/bin/python3 find_posts.py -c=artifacts/config.json
+    ```
+
+10. Create a systemd service file for FediFetcher:
+    ```bash
+    nano /etc/systemd/system/fedifetcher.service
+    ```
+    Paste the following content:
+    ```
+    [Unit]
+    Description=FediFetcher Service
+    After=network.target
+
+    [Service]
+    Type=simple
+    User=root
+    WorkingDirectory=/opt/FediFetcher
+    ExecStart=/opt/fedifetcher/bin/python find_posts.py -c=artifacts/config.json
+
+    [Install]
+    WantedBy=multi-user.target
+    ```
+
+11. Create a systemd timer file for FediFetcher:
+    ```bash
+    nano /etc/systemd/system/fedifetcher.timer
+    ```
+    Paste the following content:
+    ```
+    [Unit]
+    Description=FediFetcher Timer
+
+    [Timer]
+    OnCalendar=*-*-* *:*:00
+    Persistent=true
+
+    [Install]
+    WantedBy=timers.target
+    ```
+
+12. Reload the systemd daemon configuration:
+    ```bash
+    systemctl daemon-reload
+    ```
+
+13. Start the FediFetcher timer and enable it to start at every system boot:
+    ```bash
+    systemctl start --now fedifetcher.timer
+    ```
+
+With these steps, FediFetcher should be successfully set up on your system and automatically started to fetch posts regularly.