Cloud/hostname pre validation

[HalldorLyngmo]

📋 Description

This is an optional workflow for pre-validating hostnames in Umbraco Cloud.
Basically adds a page talking about what it's for and how to do it. As well a small section referencing custom certificates and using this optional workflow.

📎 Related Issues (if applicable)

✅ Contributor Checklist

I've followed the Umbraco Documentation Style Guide and can confirm that:

• Code blocks are correctly formatted.
• Sentences are short and clear (preferably under 25 words).
• Passive voice and first-person language (“we”, “I”) are avoided.
• Relevant pages are linked.
• All links work and point to the correct resources.
• Screenshots or diagrams are included if useful.
• Any code examples or instructions have been tested.
• Typos, broken links, and broken images are fixed.

Product & Version (if relevant)

Deadline (if relevant)

Hold off with publishing this until we relase the feature. That should happen in the next 2 weeks.

📚 Helpful Resources

• 🧾 Umbraco Contribution Guidelines
• ✍️ Umbraco Documentation Style Guide

[sofietoft]

Thanks for the PR @HalldorLyngmo !

Could you please add the article to the SUMMARY.md file?
Otherwise it will not show up on the Docs platform.

[sofietoft]

Thanks for adding the article to the SUMMARY file @HalldorLyngmo !

Could you take a look at the comments I made as well?
Also, do you have a date for when this feature is released?

[pijemcolu]

I've added a bunch of comments mainly related to the proxy use case.

[HalldorLyngmo]

Add proxying to pre-validation documentation

This has been applied already :)