[zh] add contributing/_index.md

[darielli]

[zh] add contributing/_index.md

[darielli]

/fix:format

[opentelemetrybot]

You triggered fix:format action run at https://github.com/open-telemetry/opentelemetry.io/actions/runs/9482408323

[windsonsea]

Could you provide a space between en and zh chars, to follow the style on the current pages.
You need to check from top to bottom, thanks.

[reyang]

Could you provide a space between en and zh chars, to follow the style on the current pages. You need to check from top to bottom, thanks.

Maybe a good thing to cover in the CI job.

[chalin]

The Contributing section has been reworked, but this is consistent with the given commit hash. LGTM, thanks!