Add submission # 6809

#6809

Author: ArduinoBot

registry.txt

@@ -8299,3 +8299,4 @@ https://github.com/gvp-257/SendOnlySerial.git|Contributed|SendOnlySerial
 https://github.com/satoyon/PFNFont.git|Contributed|PFNFont
 https://github.com/jaikulk14/MQGasKit.git|Contributed|MQGasKit
 https://github.com/kenchow96/faster-trig-2040.git|Contributed|faster-trig-2040
+https://github.com/nexbyteio/ZenRTC.git|Contributed|ZenRTC