docs(examples): add Dockerfiles and usage docs for demo, simple, and tutorial apps

[sidharth-chauhan]

Problem

The examples/demo, examples/simple, and examples/tutorial in react-admin did not support Docker, requiring users to manually install dependencies and configure each project. This was inconvenient, especially for DevOps users or beginners.

Solution

I have added Docker support and documentation to all three examples:

• ✅ Added Dockerfile for each example
• ✅ Added a README.md explaining how to build and run the example using Docker

This makes it easy for anyone to quickly run any example in a containerized environment.

Changes Summary

• examples/demo/Dockerfile
• examples/demo/README.md
• examples/simple/Dockerfile
• examples/simple/README.md
• examples/tutorial/Dockerfile
• examples/tutorial/README.md

Screenshots

Simple App

Demo App

Tutorial App

Checklist

• All Dockerfiles were tested locally and run successfully
• Added corresponding README files for Docker usage
• Follows contribution guidelines
• Screenshots attached for verification

[sidharth-chauhan]

“Hi! I’ve added Docker support to the examples. Would love your feedback whenever convenient. Thanks!”

[slax57]

Hi,
Thank you for your contribution.
IMHO it's pretty straightforward to create docker containers to run react-admin code, as it's a standard node.js application, so I'm not sure this requires specific config files + documentation.
On the other hand this adds code to the codebase that we won't use ourselves but will need to maintain, so I'm -1 for it.
Hence I'm closing this PR.
Thank you anyway for the contribution, and feel free to contribute to other parts of the repo.