Document webpack change: fix: sync and async wasm generation

[webpack-bot]

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

See pull request: webpack/webpack#18978

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What kind of change does this PR introduce?

bugfix

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?

Removed fetch-streaming from https://webpack.js.org/configuration/output/#outputwasmloading, this was removed a long time ago and doesn't even work