Add Value Summary and Value Type Documentation

[madsrasmussen]

📋 Description

Includes changes from #8043 . Please review and merge first.

Adds documentation for the new Value Summary and Value Type extension points/concepts

✅ 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)

CMS 17.5

Deadline (if relevant)

[AndyButland]

Looks great @madsrasmussen from my perspective. I just left one suggestion that I think makes it clearer as you read through, that you can go to the server for more information for presentation if you need to.

[AndyButland]

Suggested change

	A value type can represent any data structure, including complex objects. If your data has shape, define it accordingly and access its properties directly in `render()`. A color value with a hex code and a label, for example, lets you render a swatch alongside the name. The whole representation comes from the stored value — no server call needed:
	A value type can represent any data structure, including complex objects. If your data has shape, define it accordingly and access its properties directly in `render()`. A color value with a hex code and a label, for example, lets you render a swatch alongside the name. In this example, the representation comes from information already in the stored value — no server call is needed:

[sofietoft]

Do the changes made here also apply to version 18?

Also, are the new articles in this PR generated by (or with the assistance of) AI?
For transparency, we're tagging all articles written by or with the assistance of AI.