Document webpack change: feat: support `webpackIgnore` for `new URL()` construction

[webpack-bot]

A pull request by @alexander-akait was merged and maintainers requested a documentation change.

See pull request: webpack/webpack#18677

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What kind of change does this PR introduce?

Feature:

new URL(/* webpackIgnore: true */ "file1.css", import.meta.url)

Because we support import(/* webpackIgnore: true */ "./file.css"); we need support for this in new URL() too, otherwise it is imposible to migrate on new URL from import(...); (what we actually recommend).

Also import.meta.url is not keeping as is, it will be replaced on baseURI in such case (for modules it is new URL("./", import.meta.url), for other cases it is document.baseURI), so relative URLs will work correctly.

Did you add tests for your changes?

Yes

Does this PR introduce a breaking change?

No

What needs to be documented once your changes are merged?

Need improve our docs about this feature