Update Readme information for MacOs

[siegfriedschaefer]

Your readme is missing a hint on how to get rid of the metro openssl issue if just cloning your repo as it is in main-branch. You have to switch to the "react-native-0-69" branch if you want to use node > 17 under MacOS. Easy flow: git clone https://github.com/BabylonJS/BabylonReactNativeSample.git webxr cd webxr git checkout react-native-0-69 npm install npm run android This hint saves newcomers like me a lot of time searching the web and trying not working solutions. Please update your readme accordingly. Thank you!