docs: add note about new runtime

Author: HayesGordon

README.md

@@ -6,6 +6,22 @@
 
 ![Rive hero image](https://rive-app.notion.site/image/https%3A%2F%2Fs3-us-west-2.amazonaws.com%2Fsecure.notion-static.com%2Fff44ed5f-1eea-4154-81ef-84547e61c3fd%2Frive_notion.png?table=block&id=f198cab2-c0bc-4ce8-970c-42220379bcf3&spaceId=9c949665-9ad9-445f-b9c4-5ee204f8b60c&width=2000&userId=&cache=v2)
 
+> **🚀 New Runtime Available for Testing!**
+>
+> We're excited to announce that the new Rive React Native runtime is now public and ready for testing. Built with Nitro for improved performance and better React Native integration, this next-generation runtime leverages the new React Native architecture and will eventually be distributed on NPM under the name `@rive-app/react-native`.
+>
+> **Try it now:** https://github.com/rive-app/rive-nitro-react-native
+>
+> **Current Status:** The new package is in development preview. While it's functional and actively maintained, the API may change in future releases. We recommend testing thoroughly before using in production applications.
+>
+> **Migration Timeline:**
+>
+> - **Short term:** Complete the new runtime and unblock production usage
+> - **Medium term:** Address major concerns in this legacy package while supporting migration
+> - **Long term:** Full migration to the new package
+>
+> We're actively gathering feedback to improve the new runtime. Please share your thoughts and report any issues you encounter!
+
 A React Native runtime library for [Rive](https://rive.app).
 
 This library is a wrapper around the iOS/Android runtime, providing a component and ref pattern for React Native applications.
@@ -58,11 +74,13 @@ Check out the `example/` folder to run an example application using the Rive Rea
 - ...and more!
 
 Steps:
+
 1. Run `yarn bootstrap`
 2. cd `example`
 3. `yarn expo run:android` or `yarn expo run:ios`
 
 iOS:
+
 - You may need to run `pod install` (first time) or `pod update RiveRuntime` (updates to the underlying Rive iOS runtime) in the `example/iOS` folder to get the runtime installed or updated
 
 ## Migration Guides
@@ -114,6 +132,7 @@ Create or edit `ios/Podfile.properties.json`:
 ```
 
 Then run:
+
 ```bash
 cd ios && pod install
 ```
@@ -159,9 +178,11 @@ export default ({ config }: ConfigContext): ExpoConfig => ({
 The library resolves versions in the following order:
 
 **iOS:**
+
 1. `ios/Podfile.properties.json` → `RiveRuntimeIOSVersion`
 2. `package.json` → `runtimeVersions.ios` (default)
 
 **Android:**
+
 1. `android/gradle.properties` → `Rive_RiveRuntimeAndroidVersion`
 2. `package.json` → `runtimeVersions.android` (default)