update create-a-new-react-app.md / add bit to flexible toolchains

[jonisar]

Added Bit as an open-source tool for creating composable React applications and components. Bit can be used for creating a new React app or on top of an existing app or a system of apps. It provides out-of-the-box app and component boilerplates, dev environments, templates and tools for reactjs, and has native support for just about any tool in the React development ecosystem, and can be easily extended and customized to support more tools.

[github-actions[bot]]

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