remove OMD (discontinued)

- continued through CheckMK and OMD Labs-Edition (https://labs.consol.de/omd/)

README.md

@@ -493,7 +493,6 @@ _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`
-- [OMD](http://omdistro.org/) - The Open Monitoring Distribution.
 - [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`