[Workers] Split version overrides into dedicated page, add service bindings guidance

[yomna-shousha]

Summary

• Extracts the Version overrides section from gradual-deployments.mdx into its own dedicated page (version-overrides.mdx)
• Adds a new Service bindings section documenting that Cloudflare-Workers-Version-Overrides works on service-binding fetch() subrequests
• Clarifies that the header is not automatically propagated — the calling Worker must explicitly set it
• Adds a note that version overrides do not work with RPC calls (env.MY_SERVICE.someMethod()), since RPC has no mechanism for attaching headers
• Fixes a broken link in previews.mdx to point to the new page

Context

This builds on the work in #30733 by @thomsoncf — same customer feedback

Verified

Deployed two Workers (caller + callee) with a service binding and gradual deployment (v1=100%, v2=0%). Confirmed:

Scenario	Result
No override header	callee returns v1
Caller explicitly sets override → v2 on env.CALLEE.fetch()	callee returns v2

Files changed

• New: version-overrides.mdx — dedicated version overrides page with service bindings section
• Modified: gradual-deployments.mdx — replaced version overrides section with link to new page
• Modified: previews.mdx — updated link to point to new page

[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/product-owners, @cloudflare/wrangler, @mattietk, @cloudflare/dev-plat-leads

[github-actions]

Preview URL: https://44f5dd19.preview.developers.cloudflare.com
Preview Branch URL: https://yomna-version-overrides-service-bindings.preview.developers.cloudflare.com

Files with changes (up to 15)

Original Link	Updated Link
https://developers.cloudflare.com/workers/configuration/versions-and-deployments/version-overrides/	https://yomna-version-overrides-service-bindings.preview.developers.cloudflare.com/workers/configuration/versions-and-deployments/version-overrides/
https://developers.cloudflare.com/workers/configuration/versions-and-deployments/gradual-deployments/	https://yomna-version-overrides-service-bindings.preview.developers.cloudflare.com/workers/configuration/versions-and-deployments/gradual-deployments/
https://developers.cloudflare.com/workers/configuration/previews/	https://yomna-version-overrides-service-bindings.preview.developers.cloudflare.com/workers/configuration/previews/