Remove arkOS (discontinued)

https://arkos.io/2017/04/sunset/
Fixes https://github.com/Kickball/awesome-selfhosted/issues/1048

README.md

@@ -1172,7 +1172,6 @@ See also [Documentation Generators](#documentation-generators), [Wikimatrix](htt
 
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-  * [arkOS](https://arkos.io/) - Install arkOS to a dedicated device and host your own websites, email, files and more. ([Source Code](https://github.com/arkOScloud)) `MIT/GPL` `Nodejs/Other`
   * [Cloudron](https://cloudron.io) - Effortlessly self-host web apps on your server. ([Source Code](https://git.cloudron.io/groups/cloudron)) `AGPLv3` `Nodejs/Docker`
   * [DPlatform](https://dfabric.github.io/DPlatform-ShellCore/) - Deploy self-hosted apps easily: simple, bloat-free, independent installation. ([Source Code](https://github.com/j8r/DPlatform)) `MIT` `Shell`
   * [FreedomBone](https://github.com/bashrc/freedombone) - Home server configuration based on Debian. `GPLv3` `Shell`