docs: fix broken worker file link in zig section

[kbwo]

I fixed broken link in https://workers.wasmlabs.dev/docs/languages/zig

[vmwclabot]

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[vmwclabot]

@kbwo, we have received your signed contributor license agreement. The review is usually completed within a week, but may take longer under certain circumstances. Another comment will be added to the pull request to notify you when the merge can proceed.

[Angelmmiguel]

Thank you for your contribution @kbwo! I'm going to approve it and wait for the CLA to merge it 😄

[ereslibre]

Thanks @kbwo!

[vmwclabot]

@kbwo, VMware has approved your signed contributor license agreement.