Preamble docs are broken

[rockwotj]

See here, it looks like a streaming parameter is mixed in with the docs for Preamble. It was very confusing for me when I found this 😄

cohere-go/types.go

Lines 23 to 35 in abe8044

	// Defaults to `false`.
	//
	// When `true`, the response will be a JSON stream of events. The final event will contain the complete response, and will have an `event_type` of `"stream-end"`.
	//
	// Streaming is beneficial for user interfaces that render the contents of the response piece by piece, as it gets generated.
	//
	// Compatible Deployments: Cohere Platform, Azure, AWS Sagemaker/Bedrock, Private Deployments
	//
	// When specified, the default Cohere preamble will be replaced with the provided one. Preambles are a part of the prompt used to adjust the model's overall behavior and conversation style, and use the `SYSTEM` role.
	//
	// The `SYSTEM` role is also used for the contents of the optional `chat_history=` parameter. When used with the `chat_history=` parameter it adds content throughout a conversation. Conversely, when used with the `preamble=` parameter it adds content at the start of the conversation only.
	//
	// Compatible Deployments: Cohere Platform, Azure, AWS Sagemaker/Bedrock, Private Deployments