Tool choice docs

[mrmer1]

This pull request introduces a new section titled "Forcing Tool Use" in the documentation, which explains how to force the model to make tool calls during the tool calling step.

• A new section titled "Forcing Tool Use" is added to the documentation.
• The section describes two options for the model during the tool calling step: making tool calls or responding to a user message directly.
• It explains that setting the force_single_step parameter to True forces the model to make at least one tool call, equivalent to setting tool_choice as REQUIRED in the v2 API.
• The section also mentions that if force_single_step is True and tool_results are passed, it is equivalent to specifying NONE.
• A code snippet is provided to demonstrate how to force tool use by setting the tool_choice parameter to REQUIRED.

[github-actions]

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[github-actions]

🌿 Preview your docs: https://cohere-preview-28419bd4-fce5-40f5-b674-ce9430a832cc.docs.buildwithfern.com