Add docs for metadata and Scenarios Framework

[mattobee]

Adds a tutorial doc for metadata annotations and a guidance doc explaining the Scenarios Framework.

[Copilot]

Pull Request Overview

This PR adds new documentation for the Annotation Toolkit, specifically focusing on metadata handling in web documents. The changes introduce comprehensive tutorials for language declaration and page title annotation, along with a brief explanation of the Scenarios Framework.

• Adds a detailed tutorial on metadata annotation with focus on language and page title elements
• Introduces documentation for the Scenarios Framework used within the Annotation Toolkit
• Provides comprehensive guidance on accessibility best practices for web document metadata

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 8 comments.

File	Description
tutorials/metadata.md	Comprehensive tutorial covering language and page title metadata annotations with accessibility guidelines
basics/scenarios-framework.md	Brief documentation explaining the internal Scenarios Framework initiative

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[janmaarten-a11y]

Good job, 🤖. You found all my zero-width non-breaking spaces. Have a little merge as a treat!