add multiple api article and sidebar in open source repo

[themattwilliams]

Changes Made in Response to Feedback

• Removed unnecessary bold tags from headings as they are automatically bolded in Redocly
• Improved YAML formatting in examples for better readability

What/Why/How?

What: Added new documentation article about Arazzo and updated sidebars to include it in the navigation.

Why: Arazzo is a new OpenAPI specification for documenting workflows across multiple APIs. This documentation helps users understand how to use Arazzo to document complex API workflows, similar to how architects use circulation diagrams alongside room blueprints.

How:

• Created new article documenting-multiple-apis-using-arazzo.md with comprehensive examples and explanations
• Updated sidebars to include the new article in the navigation
• Used architectural metaphors to explain complex concepts
• Included real-world examples of Arazzo workflows

Reference

• Arazzo Specification repository
• Arazzo roadmap blog post

Testing

• Verified all Mermaid diagrams render correctly
• Checked all code examples for syntax accuracy
• Validated all internal links and references
• Tested the article in the local development environment

Screenshots (optional)

N/A - Documentation changes only

Check yourself

• Code is linted
• Tested
• All new/updated code is covered with tests

Security

• Security impact of change has been considered
• Code follows company security practices and guidelines

Note: This is a documentation-only change that doesn't affect any security-sensitive code or functionality.

[themattwilliams]

@adamaltman can you approve, or is there someone else I should ping?