Steps to reproduce (assumes ChromeVox or similar)

1. Open https://elastic.github.io/eui/#/forms/form-controls in a new tab.
2. Tab to the first textarea under the "Textarea" heading.

Actual Result

"textarea"

Expected Result

"Placeholder text textarea"

Category: #781: Elastic UI Form Controls Accessibility
Relevant WCAG Criteria: 3.3.2 Labels or Instructions