Document the gotcha for esbuild css plugin

[machour]

trafficstars

An error is thrown when using either filter for onLoad (seems like esbuild is attempting to load it as js even though "main" is pointed to index.css)

We need to document a little gotcha until we find a proper solution, see discussion here: https://github.com/remix-run/remix/pull/4130#issuecomment-1279149538

[KingSora]

@machour I think it would be good if we investigate further on this, because isolated tests show that this issue might be related to other plugins / things above esbuild. Opened an issue on esbuilds side and got the confirmation there as well. https://github.com/remix-run/remix/pull/4130#issuecomment-1280845923

[machour]

Definitely, but until then, the issue should be properly documented for our users.

Thank you again for your contribution, already using it! 🙏

[machour]

Nobody complained 🤷🏼