docs: add React Native for OpenHarmony to out-of-tree platforms (#5197)

Author: goooosun

docs/out-of-tree-platforms.md

@@ -10,6 +10,7 @@ React Native is not only for Android and iOS devices - our partners and the comm
 - [React Native macOS](https://github.com/microsoft/react-native-macos) - React Native for macOS and Cocoa.
 - [React Native Windows](https://github.com/microsoft/react-native-windows) - React Native for Microsoft's Universal Windows Platform (UWP).
 - [React Native visionOS](https://github.com/callstack/react-native-visionos) - React Native for Apple's visionOS.
+- [React Native OpenHarmony](https://atomgit.com/CPF-RN/ohos_react_native) - React Native for OpenHarmony.
 
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