Preparing for the Future with React Prereleases

Facebook uses feature flags all over the place, and I'm excited to see them appear in React's release workflow.

For those who are curious, you can see the feature flags here: https://github.com/facebook/react/blob/master/packages/share...

It looks like the current "experimental" flags relate to a recent change in concurrent mode API, and options to enable server-side rendering with suspense. (Including a feature called "selective hydration", which I'm super curious about..)