Copy-paste docs error on ChatCompletionAccumulator.JustFinishedContent

[danthegoodman1]

Seems it was copy-pasted from JustFinishedRefusal by mistake

openai-go/streamaccumulator.go

Lines 55 to 64 in c0414f1

	// JustFinishedRefusal retrieves the chat completion refusal when it is known to have just been completed.
	// The content is "just completed" when the last added chunk no longer contains a content
	// delta. If the content is just completed, the content is returned and the boolean is true. Otherwise,
	// an empty string is returned and the boolean will be false.
	func (acc *ChatCompletionAccumulator) JustFinishedContent() (content string, ok bool) {
	if acc.justFinished.state == contentResponseState {
	return acc.Choices[0].Message.Content, true
	}
	return "", false
	}

[jacobzim-stl]

Eek, thanks. Will fix!