[Meta] [New docs] Publish Elastic Design System patterns

[tkajtoch]

Summary

We want to create a new Patterns documentation section with all ready Elastic Design System patterns published.

Acceptance criteria

• Patterns section link should be added to site's header
• All ready and approved Elastic Design System patterns should be published under the Patterns section
• Patterns should not contain links to internal or private resources like Figma projects or Google Docs documents
• Patterns should be linked to relevant component docs