Add link to docs.json schema to AI tool guides

[ethanpalm]

Documentation changes

This PR links to https://mintlify.com/docs.json in all the example rules for AI assistants.

Closes https://linear.app/mintlify/issue/DOC-124/add-docsjson-reference-to-all-ai-rules

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For Reviewers

When reviewing documentation PRs, please consider:

✅ Technical accuracy

• Code examples work as written
• Commands and configurations are correct
• Links resolve to the right destinations
• Prerequisites and requirements are accurate

✅ Clarity and completeness

• Instructions are clear and easy to follow
• Steps are in logical order
• Nothing important is missing
• Examples help illustrate the concepts

✅ User experience

• A new user could follow these docs successfully
• Common gotchas or edge cases are addressed
• Error messages or troubleshooting guidance is helpful