message: chore(readme): add hidden example
diff: @@ -521,6 +521,7 @@ You can find all examples in the [example](example) folder or check out the live
  - [empty](https://reactflow.dev/empty)
  - [interaction](https://reactflow.dev/interaction)
  - [provider](https://reactflow.dev/provider)
  +- [hidden](https://reactflow.dev/hidden)
  # Development
  