fix: add contentHash to document properties

[barmac]

Description

The documentation is missing the contentHash property which is required to retrieve the stored response. But in fact, the property is set on the document variable. This PR fixes the missing documentation.

When should this change go live?

• This is a bug fix, security concern, or something that needs urgent release support. (add bug or support label)
• This is already available but undocumented and should be released within a week. (add available & undocumented label)
• This is on a specific schedule and the assignee will coordinate a release with the Documentation team. (create draft PR and/or add hold label)
• This is part of a scheduled alpha or minor. (add alpha or minor label)
• There is no urgency with this change (add low prio label)

PR Checklist

• The commit history of this PR is cleaned up, using {type}(scope): {description} commit message(s)

• My changes are for an upcoming minor release and are in the /docs directory (version 8.9).
• My changes are for an already released minor and are in a /versioned_docs directory.

• I added a DRI, team, or delegate as a reviewer for technical accuracy and grammar/style:
  • Engineering team review
  • Technical writer review via @camunda/tech-writers unless working with an embedded writer.

[github-actions]

👋 🤖 ✅ Looks like the changes were ported across versions, nice job! 🎉

You can read more about the versioning within our docs in our documentation guidelines.

[mesellings]

@giorgionaps very small change, but please just give it a TW review 🙏

[giorgionaps]

No comments from me

[mesellings]

@barmac can you please add the relevant labels - it helps us triage PRs and make sure we don't miss anything 🙏

[barmac]

OK done! I've also added the missing part for the next and 8.7 docs.

[mesellings]

Thanks @barmac - @giorgionaps please TW re-review so we can get this released (assuming it is okay from a technical pov) 🙏

[giorgionaps]

No comments from me on this one