docs: add javascript.formatter.trailingCommas

[Marukome0743]

Summary

The javascript.formatter.trailingComma option is deprecated and renamed to javascript.formatter.trailingCommas.
Then add the configuration.

Details can be checked in biomejs/biome#2492

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[Sec-ant]

Thank you, I think we should also mark trailingComma as deprecated or remove it. Do you want to help?

There're other deprecated options that possibly should also be taken care of, like indentSize and command line options like --trailing-comma in the CLI doc page.

[Marukome0743]

Thank you, I think we should also mark trailingComma as deprecated or remove it. Do you want to help?

Yup, I wanna add the warning to old options.

Warning

javascript.formatter.trailingComma is deprecated.
Use javascript.formatter.trailingCommas instead.

Or folding the old options like the below.

javascript.formatter.trailingComma (deprecated)

Print trailing commas wherever possible in multi-line comma-separated syntactic structures. Possible values:

• "all", the trailing comma is always added;
• "es5", the trailing comma is added only in places where it’s supported by older version of JavaScript;
• "none", trailing commas are never added.
  Default: "all"

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There're other deprecated options that possibly should also be taken care of, like indentSize and command line options like --trailing-comma in the CLI doc page.

I'm willing to update the docs in order to adapt version 1.8.0.
However, I wonder my changes will be overriden when #518 merged.

This PR might be just temporary update until #518.

[Sec-ant]

Fair, let's merge this first.