Added doc for systemd service config

Also updated typo/wording for confirming pwrstat service status.

README.md

@@ -3,7 +3,7 @@ Cyberpower UPS Linux daemon (pwrstat) exporter for prometheus
 
 ## Installation
 Must have Linux PowerPanel application from CyberPower already downloaded (https://www.cyberpowersystems.com/product/software/powerpanel-for-linux/)
-And make sure the ``pwrstat.service`` has been staring.
+And make sure the ``pwrstat.service`` has been started: `service pwrstat status`
 
 ### Build from source
 **Please install golang 1.16** 
@@ -25,6 +25,30 @@ Args
 sudo pwrstat-exporter --web.listen-address 8088 --web.telemetry-path /metrics
 ```
 
+## Systemd service
+Create the service config
+`nano /etc/systemd/system/pwrstat-exporter.service`
+
+```
+[Unit]
+Description=pwrstat-exporter
+
+[Service]
+TimeoutStartSec=0
+ExecStart=/usr/local/bin/pwrstat-exporter
+
+[Install]
+WantedBy=multi-user.target
+```
+Restart the systemd daemon, set the service to start on boot, and start the service manually for the first time. 
+
+`systemctl daemon-reload`
+
+`systemctl enable pwrstat-exporter`
+
+`service pwrstat-exporter start`
+
 ## Dashboard
 You can import the dashboard using ``grafana-dashboard.json``
 ![grafana](/image/grafana.png)
+