CSP configuration and whitelist domains

[ethanpalm]

Documentation changes

This PR adds a page about CSP configuration.

Closes https://linear.app/mintlify/issue/DOC-150/create-a-document-for-whitelisting-necessary-domains

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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
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• Nothing important is missing
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✅ User experience

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• Common gotchas or edge cases are addressed
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[mayankshouche]

one more small comment, but otherwise lgtm!