[R2] Removing R2 with Workers example, adding redirect to relevant page

[Oxyjun]

Summary

Screenshots (optional)

Documentation checklist

• The documentation style guide has been adhered to.
• If a larger change - such as adding a new page- an issue has been opened in relation to any incorrect or out of date information that this PR fixes.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.

[windsurf-bot]

1 file skipped due to size limits:

• public/__redirects

💡 To request another review, post a new comment with "/windsurf-review".

[github-actions]

This PR changes current filenames or deletes current files. Make sure you have redirects set up to cover the following paths:

• /r2/examples/demo-worker/

[github-actions]

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

Pattern	Owners
/public/__redirects	@GregBrimble, @KianNH, @pedrosousa, @WalshyDev, @cloudflare/pcx-technical-writing
/src/content/docs/r2/	@oxyjun, @elithrar, @jonesphillip, @aninibread, @harshil1712, @cloudflare/workers-docs, @cloudflare/pcx-technical-writing

[github-actions]

Preview URL: https://5e68f33c.preview.developers.cloudflare.com
Preview Branch URL: https://jun-r2-remove-bad-example.preview.developers.cloudflare.com

Files with changes (up to 15)

Original Link	Updated Link
https://developers.cloudflare.com/r2/examples/demo-worker/	https://jun-r2-remove-bad-example.preview.developers.cloudflare.com/r2/examples/demo-worker/