Summary

Adds mandatory applies_to (and products) frontmatter to all reference docs and adds section-level applies_to where content is stack-only, per the Docs Versioning contributor guidelines and applies_to syntax.

Relates to #256

Generative AI disclosure

1. Did you use a generative AI (GenAI) tool to assist in creating this contribution?

• Yes
• No

2. If you answered "Yes" to the previous question, please specify the tool(s) and model(s) used (e.g., Google Gemini, OpenAI ChatGPT-4, etc.).

Tool(s) and model(s) used: Claude Sonnet 4.5 using Cursor to double-check the updated files, write PR description