Add childEnvironments to Vite plugin API docs

[jamesopstad]

Summary

Screenshots (optional)

Documentation checklist

• Is there a changelog entry (guidelines)? If you don't add one for something awesome and new (however small) — how will our customers find out? Changelogs are automatically posted to RSS feeds, the Discord, and X.
• The change adheres to the documentation style guide.
• If a larger change - such as adding a new page- an issue has been opened in relation to any incorrect or out of date information that this PR fixes.
• Files which have changed name or location have been allocated redirects.

[github-actions]

This pull request requires reviews from CODEOWNERS as it changes files that match the following patterns:

Pattern	Owners
/src/content/docs/workers/	@cloudflare/workers-docs, @GregBrimble, @irvinebroque, @mikenomitch, @korinne, @WalshyDev, @cloudflare/deploy-config, @cloudflare/pcx-technical-writing, @cloudflare/wrangler, @mattietk

[github-actions]

Preview URL: https://054a9e2f.preview.developers.cloudflare.com
Preview Branch URL: https://james-vite-plugin-child-environments.preview.developers.cloudflare.com

Files with changes (up to 15)

Original Link	Updated Link
https://developers.cloudflare.com/workers/vite-plugin/reference/api/	https://james-vite-plugin-child-environments.preview.developers.cloudflare.com/workers/vite-plugin/reference/api/

[github-actions]

Hey there, we've marked this pull request as stale because there's no recent activity on it. This label is helps us identify PRs that might need updates (or to be closed out by our team if no longer relevant).