fix(systemd/readme): Improve README documentation and fix UPS status retrieval in systemd service

ts/systemd.ts

@@ -170,9 +170,16 @@ WantedBy=multi-user.target
    */
   private async displayUpsStatus(): Promise<void> {
     try {
-      const upsStatus = await this.daemon.getConfig().snmp;
+      const config = this.daemon.getConfig();
       const snmp = this.daemon.getNupstSnmp();
-      const status = await snmp.getUpsStatus(upsStatus);
+      
+      // Create a test config with appropriate timeout, similar to the test command
+      const snmpConfig = { 
+        ...config.snmp,
+        timeout: Math.min(config.snmp.timeout, 10000) // Use at most 10 seconds for status check
+      };
+      
+      const status = await snmp.getUpsStatus(snmpConfig);
       
       console.log('┌─ UPS Status ───────────────────────────────┐');
       console.log(`│ Power Status: ${status.powerStatus}`);