Update README for setup guides #5354
Description
It looks like the link to environment setup is broken and needs to be updated.
The React Native documentation contains detailed instructions on how to prepare your computer for React Native development. Follow the instructions in the "React Native CLI Quickstart" for your specific platform.
It should link to current documentation perhaps: https://reactnative.dev/docs/set-up-your-environment?platform=ios#installing-dependencies
Also the other details regarding AIRBITZ_API_KEY may need updating/review.
Move yarn start to run the bundler after iOS/Android specific setups (yarn prepare.ios).