content: improve components docs for the alignment property

### URL

https://ionicframework.com/docs/api/

### Issue Description

The following components have the `alignment` property documented at these links:
- [Checkbox](https://ionicframework.com/docs/api/checkbox#alignment)
- [Radio](https://ionicframework.com/docs/api/radio#alignment)
- [Toggle](https://ionicframework.com/docs/api/toggle#alignment)

The playground examples currently only demonstrate how the `alignment` property works horizontally when the label placement is set to `stacked`. However, they do not show how the `alignment` property affects vertical alignment with the `fixed`, `start`, and `end` label placements.

We should add examples demonstrating how `alignment` works vertically, similar to the following, for each component:

```html

```

> [!NOTE]
> This is just one example of how to illustrate the usage. It doesn't have to be exactly like the example provided.

Start with the API documentation playground examples for Checkbox, Radio, and Toggle at the linked alignment sections. Compare the existing stacked-label examples, then add vertical-alignment examples for the fixed, start, and end label placements; done means each component demonstrates the alignment behavior clearly.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.