fix(conversation): update api docs + drive more clarity

[sicoyle]

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Description

This is to correct conversation api docs to better drive end user clarify on what the fields mean/do.

Issue reference

n/a

[Copilot]

Pull request overview

This PR updates the Conversation API reference to better clarify the intended usage of parameters vs metadata in the Alpha2 conversation endpoint, and improves guidance around tool choice behavior.

Changes:

• Refines the request-body field descriptions for parameters (typed overrides) and metadata (OpenAI-like tagging metadata).
• Adds toolChoice: none to the documented tool choice options and updates metadata examples to reflect tagging use-cases.
• Adjusts the URL query metadata example away from configuration/auth-style usage.

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[msfussell]

LGTM. @marcduiker PTAL

[marcduiker]

LGTM