[Accessibility Docs] Media object

Using [this template](https://docs.google.com/document/d/1IwFMfJrTfJPXDcVJfLWXYkw-pjgWhBWo4GX8X098Q64/edit#), create accessibility docs for [Media object](https://vanillframework.io/docs/patterns/media-object)

Start with the accessibility documentation template and the Media object documentation page linked in the issue. Create the Media object accessibility docs following the template; done means the new documentation covers that component and matches the requested format.

Written by the indexing model from the issue text.