Document a preference for starting from scratch

[JoshuaKGoldberg]

Overview

I've been suggesting to people on Twitter (and @beenotung mentioned something like this too) that if they have the time, the most pleasant way to convert from TSLint to ESLint is:

1. Delete any existing TSLint configurations and uninstall its packages
2. Install the eslint, @typescript-eslint/parser, and @typescript-eslint/eslint-plugin packages
3. Create an .eslintrc.js file that extends from @typescript-eslint/recommended
4. Run ESLint on your files
5. Disable any newly complaining ESLint rule in your .eslintrc.js and file an issue/ticket/what-have-you to get back to it later

Actual Behavior

No such documentation, which implies that directly using this package is the recommended way to convert.

Expected Behavior

This package works best when you have a very finely tuned TSLint configuration and not enough time to start from scratch. But, TSLint has some legacy recommendations in its rules, and not starting from scratch means you might miss out on some great new rules.

[JoshuaKGoldberg]

Oh, funny, I already filed an equivalent of this issue! 😅 Dup of #301.