Add openITCOCKPIT to Monitoring section (#510)

Co-authored-by: Rabenherz112 <rabenherz@theravenhub.com>
Co-authored-by: nodiscc <nodiscc@gmail.com>

README.md

@@ -489,6 +489,7 @@ _Related: [Metrics & Metric Collection](#metrics--metric-collection)_
 - [Netdata](https://www.netdata.cloud/) - Distributed, real-time, performance and health monitoring for systems and applications. Runs on Linux, FreeBSD, and MacOS. ([Source Code](https://github.com/netdata/netdata)) `GPL-3.0` `C`
 - [NetXMS](https://www.netxms.org/) - Open Source network and infrastructure monitoring and management. ([Source Code](https://github.com/netxms/netxms)) `LGPL-3.0/GPL-3.0` `Java/C++/C`
 - [Observium Community Edition](http://www.observium.org/) - Network monitoring and management platform that provides real-time insight into network health and performance. `QPL-1.0` `PHP`
+- [openITCOCKPIT Community Edition](https://openitcockpit.io/) - Monitoring Suite featuring seamless integrations with Naemon, Checkmk, Grafana and more. ([Demo](https://demo.openitcockpit.io/), [Source Code](https://github.com/it-novum/openITCOCKPIT)) `GPL-3.0` `deb/Docker`
 - [Performance Co-Pilot](http://pcp.io) - Lightweight, distributed system performance and analysis framework. ([Source Code](https://github.com/performancecopilot/pcp)) `LGPL-2.1/GPL-2.0` `C`
 - [PHP Server Monitor](https://www.phpservermonitor.org/) - Open source tool to monitor your servers and websites. ([Source Code](https://github.com/phpservermon/phpservermon)) `GPL-3.0` `PHP`
 - [PhpSysInfo](https://phpsysinfo.github.io/phpsysinfo/) - A customizable PHP script that displays information about your system nicely. ([Source Code](https://github.com/phpsysinfo/phpsysinfo)) `GPL-2.0` `PHP`