add maap foundry design doc

[PratibhaShrivastav18]

Description

Please add an informative description that covers that changes made by the pull request and link all relevant issues.

If an SDK is being regenerated based on a new API spec, a link to the pull request containing these API spec changes should be included above.

All SDK Contribution checklist:

• The pull request does not introduce [breaking changes]
• CHANGELOG is updated for new features, bug fixes or other significant changes.
• I have read the contribution guidelines.

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• Title of the pull request is clear and informative.
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Testing Guidelines

• Pull request includes test coverage for the included changes.

[Copilot]

Pull request overview

This PR adds a design document for the MaaP (Models-as-a-Platform) on Foundry SDK changes, covering modifications to azure-ai-ml (publisher side) and azure-mgmt-cognitiveservices (consumer side) packages.

Changes:

• Adds a new Markdown design document describing new entities, field additions, YAML examples, SDK usage samples, and open blocking prerequisites for MaaP on Foundry.

[Copilot]

Section numbering skips from '4. Dependency Chain' to '6. Open Items' — there is no section 5. This should be renumbered to '## 5. Open Items' for consistency.

Suggested change

	## 6. Open Items
	## 5. Open Items