Unable to add documentation without a sample control

### Describe the bug

Some toolkit components do not have sample controls, but do have documentation that needs to be available to end users. For example, https://github.com/CommunityToolkit/Labs-Windows/pull/438.

### Steps to reproduce

```text
n/a
```

### Expected behavior

Devs should be able to write markdown docs without an interactive sample.

### Screenshots

_No response_

### Code Platform

- [ ] UWP
- [ ] WinAppSDK / WinUI 3
- [ ] Web Assembly (WASM)
- [ ] Android
- [ ] iOS
- [ ] MacOS
- [ ] Linux / GTK

### Windows Build Number

- [ ] Windows 10 1809 (Build 17763)
- [ ] Windows 10 1903 (Build 18362)
- [ ] Windows 10 1909 (Build 18363)
- [ ] Windows 10 2004 (Build 19041)
- [ ] Windows 10 20H2 (Build 19042)
- [ ] Windows 10 21H1 (Build 19043)
- [ ] Windows 11 21H2 (Build 22000)
- [ ] Other (specify)

### Other Windows Build number

_No response_

### App minimum and target SDK version

- [ ] Windows 10, version 1809 (Build 17763)
- [ ] Windows 10, version 1903 (Build 18362)
- [ ] Windows 10, version 1909 (Build 18363)
- [ ] Windows 10, version 2004 (Build 19041)
- [ ] Other (specify)

### Other SDK version

_No response_

### Visual Studio Version

_No response_

### Visual Studio Build Number

_No response_

### Device form factor

_No response_

### Additional context

_No response_

### Help us help you

Yes, I'd like to be assigned to work on this item.

issueではファイルもテストも特定されていません。まず、リンクされているPR 438とリポジトリのドキュメントワークフローを確認してください。コンポーネントにサンプルコントロールがない場合でもMarkdownドキュメントを追加できれば完了です。

索引モデルが issue の本文から書いたものです。