docs(configuration): add documentation about mozaic.config.js

[AdeoRemiDoolaeghe]

I have read the contributing guidelines

• [x] Yes
• [ ] No

Does this PR introduce a breaking change?

• [ ] Yes
• [x] No

Describe the changes

Explains how to define the Mozaic configuration file, depending on your module system (ESM/CommonJS)

GitHub issue number or Jira issue URL: N/A

Other information

I'm clearly open to changes, as I had to make choices on my own that could not fit very well with the Mozaic way. Don't hesiate to propose changes

[AdeoRemiDoolaeghe]

That's a good idea to rethink how my proposition is organized.

As I'm not sure to understand precisely what you meant, I'll try to rephrase, so you can confirm or not.

Your suggestion is adding a new paragraph before the one called mozaic.config.js to explain the two modules systems, and how it impacts the naming of the file. Then, keep the rest of the documentation as before. Is that it?

[dmartinds]

exactly what you said @AdeoRemiDoolaeghe 👍

[AdeoRemiDoolaeghe]

I've made a new proposition. Don't hesitate to propose changes this time too.

[dmartinds]

👏 Great contribution !

All good for me.