log management: add rsyslog (#468)

README.md

@@ -469,6 +469,7 @@ _See also: [awesome-selfhosted/Database Management](https://github.com/awesome-s
 - [Flume](https://flume.apache.org/) - distributed, reliable, and available service for efficiently collecting, aggregating, and moving large amounts of log data. ([Source Code](https://github.com/apache/flume)) `Apache-2.0` `Java`
 - [GoAccess](https://goaccess.io/) - Real-time web log analyzer and interactive viewer that runs in a terminal or through the browser. ([Source Code](https://github.com/allinurl/goaccess)) `MIT` `C`
 - [Loki](https://grafana.com/oss/loki/) - Log aggregation system designed to store and query logs from all your applications and infrastructure. ([Source Code](https://github.com/grafana/loki)) `AGPL-3.0` `Go`
+- [rsyslog](https://www.rsyslog.com/) - Rocket-fast system for log processing. ([Source Code](https://github.com/rsyslog/rsyslog)) `GPL-3.0` `C`
 
 
 ### Mail Clients