Add docs and changelog entry for Wrangler secrets property

[jamesopstad]

Summary

Add docs and changelog entry for experimental Wrangler secrets property.

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• If a larger change - such as adding a new page- an issue has been opened in relation to any incorrect or out of date information that this PR fixes.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 PR requires additional review attention because it affects the following areas:

Partials

This PR updates partial files, which are pieces of content used across multiple files in our Render component.

• workers/secrets-in-dev - view affected files

[github-actions]

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

Pattern	Owners
/src/content/changelog/	@cloudflare/pm-changelogs, @cloudflare/pcx-technical-writing
/src/content/docs/workers/	@cloudflare/workers-docs, @GregBrimble, @irvinebroque, @mikenomitch, @korinne, @WalshyDev, @cloudflare/deploy-config, @cloudflare/pcx-technical-writing, @cloudflare/wrangler, @mattietk, @cloudflare/dev-plat-leads
/src/content/docs/workers/wrangler/	@cloudflare/wrangler, @irvinebroque, @cloudflare/pcx-technical-writing
/src/content/partials/workers/	@cloudflare/workers-docs, @GregBrimble, @irvinebroque, @mikenomitch, @WalshyDev, @cloudflare/deploy-config, @cloudflare/pcx-technical-writing, @cloudflare/wrangler, @mattietk

[github-actions]

Preview URL: https://0b916ad5.preview.developers.cloudflare.com
Preview Branch URL: https://james-secrets-property.preview.developers.cloudflare.com

Files with changes (up to 15)

Original Link	Updated Link
https://developers.cloudflare.com/workers/wrangler/configuration/	https://james-secrets-property.preview.developers.cloudflare.com/workers/wrangler/configuration/
https://developers.cloudflare.com/changelog/2026-03-24-secrets-config-property/	https://james-secrets-property.preview.developers.cloudflare.com/changelog/2026-03-24-secrets-config-property/
https://developers.cloudflare.com/workers/configuration/secrets/	https://james-secrets-property.preview.developers.cloudflare.com/workers/configuration/secrets/