docs: for PR #5390

ACKNOWLEDGEMENTS.md

@@ -859,3 +859,4 @@ Further device support has been made with the assistance of users. Please consid
 - [agigante80](https://github.com/agigante80) for contributing support for Ovlaim 809 ceiling fan light.
 - [robelmes](https://github.com/robelmes) for contributing improvements to ZG-205W presence sensors.
 - [pdwonline](https://github.com/pdwonline) for contributing improvements to Mypin 6L pet feeder.
+- [spokemon](https://github.com/spokemon) for contributing support for Omni X Duplex water heater.

DEVICES.md

@@ -237,6 +237,7 @@
 - Neopower Black Diamond all-in-one heat pump water heater
 - Nulite NL-B245 monobloc heat pump
 - Oekoboiler RS series heat pump water heater
+- Omni X Duplex water heater
 - Powerworld PW040, PW060, PWS58330, PWS58410 air+water heat pumps
 - Rinnai Enviroflo heat pump water heater
 - Sanden GAU-A45HPD WiFi heat pump controller