Bold and italic formatting for notifications

On https://grafana.com/docs/grafana/latest/alerting/configure-notifications/template-notifications/ , it says that with a notification template you can:
```
Format text with bold and italic styles, and add or remove line breaks.
```

If this is possible, please document **how** to do it.

Or, if it is not possible, I guess the documentation should say something like "you can not use any HTML or Markdown formatting, only plain text will be rendered".

I notice that the default template rendered for email does have some formatting.

Background: I'm trying to create an email notification, and am wondering how I can format the text. These would be nice, if available:
* bold
* italic
* HTML link with title, e.g. `[Link title](URL)`
* bullet point lists
* "code" blocks, like:
```
foo
bar
baz
```

I blindly tried things like `**stars for bold text**` or `bold text with html tag`, to no avail.

Start with the notification template documentation at the linked Grafana page and compare its formatting claims with the default email template rendering. Determine which bold, italic, link, list, code-block, and line-break forms are supported, then update the documentation with the syntax or clearly state that only plain text is rendered.

Written by the indexing model from the issue text.