fix(#176): tailwind v3.x safelisting

[MichalBryxi]

The safelist won't work with JIT the way it worked before, because:

The safelist option does not support regular expressions. Because no CSS is generated by default, the safelist has to be a list of complete class names. It’s not possible to safelist a regular expression, because there is not a pre-generated list of class names to match against that regular expression.

From tailwind v3.x the documentation hints that safelist using regular expressions matching would work.

Fixes #176

[MichalBryxi]

I'm not sure whether it's responsibility of this addon to educate users to put respective paths into content key of tailwind config, as all their styles would be purged without it anyway. But to give a hint:

'use strict';
// located in <app root>/config/tailwind/

const path = require('path');

const appRoot = path.join(__dirname, '../../');
const appEntry = path.join(appRoot, 'app');
const relevantFilesGlob = '**/*.{html,js,ts,hbs,gjs,gts}';

module.exports = {
  content: [path.join(appEntry, relevantFilesGlob)],
  safelist: [ ... ]
}

[josemarluedke]

@MichalBryxi Thanks for the PR.

I think that could be a section in the documentation where we give another option instead of safelist. If we set content and include node_modules/@frontile, that would work as well.