Expose example of README.md into an example module.

Expose example from README into module

This ticket is to add a proposal to add an extrafield in a example module.

In some modules, see example Entity meta relation, the maintainers expose a module with an example that can be used out of the box.

Should be great if the example you have at README.md goes straight into that module. It would be more straighforward for developers. Please, consider do the example or tell if we can help with that.