doc: doc/api/modules.md needs a better explanation of `exports`

[Trott]

• Version: v8.0.0-pre
• Platform: all
• Subsystem: doc

The Modules doc needs a better explanation of the utility of exports vs. module.exports. If that's too much detail for the API doc, then perhaps we can write a guide in doc/guides and link to it.

[sam-github]

@Trott #9622 (waiting @jasnell to clear his changes requested state)

[wademauger]

Is this still an open issue, now that #9622 is merged? @sam-github

[Trott]

Is this still an open issue, now that #9622 is merged? @sam-github

I'd say we can close this and open a new issue if there are specific deficiencies in the current doc that should be addressed.