resolve.alias: document replacement for deprecated null-loader regexp matching

[juliangilbey]

The docs say that null-loader is deprecated and gives an example of how to do it:

webpack.js.org/src/content/configuration/resolve.mdx

Line 124 in 3553600

W> [`null-loader`](https://github.com/webpack-contrib/null-loader) is deprecated in webpack 5. use `alias: { xyz$: false }` or absolute path `alias: {[path.resolve(__dirname, './path/to/module')]: false }`

webpack.js.org/src/content/configuration/resolve.mdx

Lines 144 to 154 in 3553600

	```js
	module.exports = {
	//...
	resolve: {
	alias: {
	'ignored-module': false,
	'./ignored-module': false,
	},
	},
	};
	```

But null-loader can also use regexps to drop files, like this:

module.exports = {
  //...
  module: {
    rules: [
      {
        test: /\.woff2(\?v=\d+\.\d+\.\d+)?$/,
        use: 'null-loader'
      },
    ]
  },
};

It would be helpful if the resolve.alias documentation could give an example of how to handle such a case. I think that the following would be the appropriate replacement, but I am far from certain that the resolver treats the alias as a regexp:

module.exports = {
  //...
  resolve: {
    alias: {
      '\\.woff2(\\?v=\\d+\\.\\d+\\.\\d+)?$': false,
    },
  },
};

[snitin315]

resolve.alias doesn't accept RegExp paths