Block documentation does not list allowed values for variant prop or explain aria-label use.

[danielck]

The Problem

The Block component has a variant prop which only supports specific values ('default','div','span','section','header','nav','main','footer'). This is not communicated clearly in the prop documentation.

Also, e.g. <section> requires an aria-label to be interpreted as a landmark by many assistive technology, and nav elements should have aria-labels when there are multiple navigation blocks of differing type on the same page.

Proposed Solution

• Rewrite the prop description of variant to explain that possible values are 'default','div','span','section','header','nav','main' and 'footer'.
• Make it explicit that attributes like aria-label, aria-labelledby etc can be used.