docs: add cluster templates tutorial skeleton

[brent-eritou]

✅ Pull Request Checklist

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Checklist

• The PR description in the Describe the Change section explains what changed and
  provides any additional context.
• A Jira ticket is provided in the Jira Tickets section AND in the PR title. If this PR has
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Good job! 👏👏👏

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📝 Describe the Change

add cluster templates tutorial skeleton

Include problem statement, dev and prod context,
workflow options, cost warning, outcomes, and
section header placeholders.

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💻 Changed Pages

• Add Preview URL for Page

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🎫 Jira Tickets

DOC-2542