OKF domain.md addition

Hi Team,
For okf bundles I have one thought it would be great if all bundles have a domain.md which will tell you to which team or person the knowledge belongs to

```
okf bundle/
|--------index.md
|--------domain.md
```

It will be more useful to organisations to maintain their internal okf bundles

sample `domain.md`

```
---
type: KnowledgeDomain
title:
description:
resource:
tags: [, ]
timestamp:
owner:
team: # OR: person: for an individual domain
contact: <#slack-channel or email>
capabilities: # what questions this domain answers (Registry routes on these)
-
-
entities: # named systems / products / services in this domain
-
-
audience: # human-readable intended audience — NOT enforced access
-
---

# Overview

# Components

* [](/​/components/.md) — .

# Playbooks

* [](/​/playbooks/.md) — .
``

The payload names no files or tests, so start by locating the existing OKF bundle structure and metadata documentation. Use the proposed domain.md example as the specification; done means the expected layout and domain ownership metadata are defined consistently for bundles, with relevant repository examples or documentation updated.

Written by the indexing model from the issue text.