docs: clarify correct usage of accessibilityRole "link" (fixes #3215)

[supunyasanthaofficial]

Fixes #3215.

Summary

The current documentation for accessibilityRole="link" and role="link" only says that the element should be treated as a link. This can be confusing when deciding whether to use link or button for in-app navigation.

This PR clarifies that link should be used for elements that open an external URL or web page, while buttons should be used for in-app navigation and actions.

Changes

• Updated the link descriptions in docs/accessibility.md to explain when to use link instead of button.
• Applied the same changes to the versioned docs from 0.77 through 0.87.

Test Plan

• Ran ESLint on docs/accessibility.md.
• Verified that the Docusaurus production build succeeds.

[Simek]

Thanks for the update! 👍