enh(webpack-scaffold): improve prompt and doc

[misterdev]

What kind of change does this PR introduce?
Slight improvement to the webpack-cli init user experience:

• improved defaults (see Scaffold: Better defaults for webpack-cli init questions #788)
• improved messages

Did you add tests for your changes?
Yes

If relevant, did you update the documentation?
Yes, also improving formatting and descriptions

Summary
#788

[webpack-bot]

Thank you for your pull request! The most important CI builds succeeded, we’ll review the pull request soon.

[webpack-bot]

@misterdev Thanks for your update.

I labeled the Pull Request so reviewers will review it again.

@ematipico Please review the new changes.

[misterdev]

Thanks @ematipico!

[misterdev]

I've found an incorrect example in packages/webpack-scaffold/README.md that wasn't covered by this PR. I've included it and taken the occasion to also update the Confirm API according to this PR and slightly improving formatting and consistency.

[ematipico]

Amazing contribution! Thank you!