message: docs(readme): add examples
diff: @@ -502,6 +502,8 @@ You can find all examples in the [example](example) folder or check out the live
  - [custom node](https://react-flow.netlify.app/custom-node)
  - [horizontal](https://react-flow.netlify.app/horizontal)
  - [stress](https://react-flow.netlify.app/stress)
  +- [validation](https://react-flow.netlify.app/validation)
  +- [provider](https://react-flow.netlify.app/provider)
  - [edges](https://react-flow.netlify.app/edges)
  - [empty](https://react-flow.netlify.app/empty)
  - [inactive](https://react-flow.netlify.app/inactive)
  