rg-2372: Update allow list to include R2 URL (#21867)

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## Description
Registry is exploring using a new domain to serve data in more efficient
way.

## Related issues or tickets
https://docker.atlassian.net/browse/RG-2372
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## Reviews

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- [ ] Technical review
- [ ] Editorial review
- [ ] Product review

Author: jcarter3

content/manuals/desktop/setup/allow-list.md

@@ -29,5 +29,6 @@ This page contains the domain URLs that you need to add to a firewall allowlist
 |https://hub.docker.com| Docker Pull/Push |
 |https://registry-1.docker.io| Docker Pull/Push |
 |https://production.cloudflare.docker.com| Docker Pull/Push |
+|https://docker-images-prod.r2.cloudflarestorage.com| Docker Pull/Push |
 |https://docker-pinata-support.s3.amazonaws.com| Troubleshooting |
 |https://api.dso.docker.com| Docker Scout service |