How to show viewport on the docs page?

[zaleGZL]

Describe the bug
How to show viewport on the docs page? The canvas page has viewport options，But the documentation page is not。Is this a bug or does it require additional configuration?

Screenshots
The canvas page has viewport options.

But the documentation page is not。

Code snippets

import { configure, addParameters } from '@storybook/react'
import { DocsPage, DocsContainer } from '@storybook/addon-docs/blocks'
import { INITIAL_VIEWPORTS } from '@storybook/addon-viewport'
import '../src/index.less'

addParameters({
    viewport: {
        viewports: INITIAL_VIEWPORTS
    },
    docs: {
        container: DocsContainer,
        page: DocsPage
    }
})

[shilman]

See #6700 for the general issue

[ndelangen]

This is currently not yet possible, maybe after 7.0.

We're open to ideas on how to implement this.