[Coding Challenge]: Collaborative Real Time (Text) Editor

## Hello @shiffman,

### I challenge you to create a collaborative real time editor which allows multiple users to work on one code, text file or whatever they want to work on! The _Google drive_ is a good example so you could check that out!

### I also have some preferences:
- [ ] I would like you to start from scratch (Of course you can use libraries like _P5js_ and _NodeJS_)
- [ ] make it **not** use other websites's services like _Firebase_ or _Pusher_, just a server running on your computer (preferably using _Sockets.io_).
- [ ] I hope you can add a timeline where you can undo and redo actions.

### I didn't get anything working myself so I hope you get more succes!!!

No se identifican archivos, pruebas ni puntos de entrada. Empieza por acotar los requisitos del editor similar a Google Drive en torno a NodeJS, Socket.io, las restricciones de local-server y la línea de tiempo de undo/redo solicitada. Para darlo por terminado sería necesario acordar el alcance de la edición multiusuario y el comportamiento del historial.

Escrito por el modelo de indexación a partir del texto del issue.