🚀 Feature: Stop publishing the demo on npm

[JoshuaKGoldberg]

Bug Report Checklist

• I have pulled the latest main branch of the repository.
• I have searched for related issues and found none that matched my issue.

Overview

I noticed while working on #89 & fixing up a few subsequent release issues that this package publishes the full demo/index.html (formerly, index.html) to npm. From...

• https://www.npmjs.com/package/package-json-validator/v/0.6.5?activeTab=code, that includes: app.js, base64.js, index.html, robots.txt
• https://www.npmjs.com/package/package-json-validator/v/0.6.8?activeTab=code: those are moved to the demo/ directory

I don't think folks who are installing this on npm need the demo. It's extra bloat in node_modules/ that we can get rid of.

Let's remove the demo/ directory from the package.json "files" entry:

https://github.com/JoshuaKGoldberg/package.json-validator/blob/84f76891ebc023ef43dcfd9a62c382f842887dea/package.json#L40

Additional Info

💖

[github-actions]

🎉 This is included in version v0.7.2 🎉

The release is available on:

• GitHub releases
• npm package (@latest dist-tag)

Cheers! 📦🚀