add overviews to bpmn elements

[christinaausley]

Description

Related to https://github.com/bpmn-io/internal-docs/issues/805.

@philippfromme Let me know what you think here. Once approved, I can backport.

When should this change go live?

• This change is not yet live and should not be merged until {ADD_DATE} (apply hold label or convert to draft PR)?
• There is no urgency with this change.
• This change or page is part of a marketing blog, conference talk, or something else on a schedule.
• This functionality is already available but undocumented.
• This is a bug fix or security concern.

PR Checklist

• I have added changes to the relevant /versioned_docs directory, or they are not for an already released version.
• I have added changes to the main /docs directory (aka /next/), or they are not for future versions.
• My changes require an Engineering review, and I've assigned an engineering manager or tech lead as a reviewer, or my changes do not require an Engineering review.
• My changes require a technical writer review, and I've assigned @christinaausley as a reviewer, or my changes do not require a technical writer review.

[christinaausley]

Related to https://github.com/bpmn-io/internal-docs/issues/805.

@philippfromme Let me know what you think here. Once approved, I can backport as I see the issue is now closed.

[akeller]

Need any help here? This looks stalled.

[christinaausley]

@philippfromme @CatalinaMoisuc mind having a quick review here sometime this week?

[philippfromme]

@christinaausley I will have a look today! 👀

[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.

[philippfromme]

Looking good now! 👏🏻

[CatalinaMoisuc]

@philippfromme @christinaausley I assume that this PR can be merged since it was already reviewed by one bpmn.io core expect, no need for an extra review from my side, correct?