Update installation.mdx

Author: drcmda

docs/getting-started/installation.mdx

@@ -8,7 +8,8 @@ nav: 1
 npm install three @react-three/fiber
 ```
 
-> Fiber is compatible with React v18.0.0+ and works with ReactDOM and React Native.
+> [!WARNING]  
+> Fiber is compatible with React v18 and v19 and works with ReactDOM and React Native. Fiber is a React renderer, it must pair with a major version of React, just like react-dom, react-native, etc. @react-three/fiber@8 pairs with react@18, @react-three/fiber@9 pairs with react@19.
 
 Getting started with React Three Fiber is not nearly as hard as you might have thought, but various frameworks may require particular attention.