add description for communication/custom communication systems

- https://github.com/awesome-selfhosted/awesome-selfhosted/issues/2984

README.md

@@ -305,11 +305,15 @@ _See also: [Comparison of CalDAV and CardDAV implementations - Wikipedia](https:
 
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+[Communication software](https://en.wikipedia.org/wiki/Communication_software) used to provide remote access to systems and exchange files and messages in text, audio and/or video formats between different computers or users.
+
 
 ### Communication - Custom Communication Systems
 
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+Communication software using their own custom procols.
+
 - [BluetoothCommunicatorExample](https://github.com/niedev/BluetoothCommunicatorExample) - Bluetooth LE chat app to communicate between android devices with P2P architecture. ([Clients](https://github.com/niedev/RTranslator)) `Apache-2.0` `Java`
 - [Centrifugo](https://centrifugal.dev/) - Language-agnostic real-time messaging (Websocket or SockJS) server. ([Demo](https://github.com/centrifugal/centrifugo#demo), [Source Code](https://github.com/centrifugal/centrifugo)) `MIT` `Go`
 - [Chaskiq](https://chaskiq.io) - Full featured livechat, helpcenter and CRM as an alternative to Intercom & Drift, Crisp and others. ([Source Code](https://github.com/chaskiq/chaskiq)) `AGPL-3.0` `Ruby`