Add Quietbench tools to README

[Aniket3477]

Adds two Quietbench tools to the README:

1. Regex section: Quietbench Regex Tester - live regex testing with match highlighting and plain-English pattern explanations
2. Transformation section: Quietbench JSON Formatter - format, validate, and minify JSON instantly in the browser

Both tools are:

• 100% browser-based, no downloads
• Direct links to specific tools
• Completely free, no signup required
• No data sent to server, runs entirely client-side

[github-actions]

Hey Aniket3477! Thanks for your submission! 🚀

To keep awesome-devtools instantly accessible for everyone, all tools must be:

• Browser-based — no downloads or native app installs
• Direct link — goes straight to the tool (not a multi-tool landing page)
• 100% free — no signups, trials, paywalls, or usage limits

Please make sure your PR meets these criteria. It may take some time for your submission to be reviewed — you can occasionally comment with a "bump" to bring more attention to it.

Thanks for contributing! 🙌