docs: correct SimpleLoggerAdvisor documentation

[dev-jonghoonpark]

Issue

In https://docs.spring.io/spring-ai/reference/api/chatclient.html,
The SimpleLoggerAdvisor class documentation incorrectly shows a constructor signature:

SimpleLoggerAdvisor(
    Function<AdvisedRequest, String> requestToString,
    Function<ChatResponse, String> responseToString
)

However, the actual constructor includes an additional parameter, int order.

Additionally, the AdvisedRequest class does not include a variable named userText.

Correction

Update the documentation to reflect the correct constructor:

SimpleLoggerAdvisor(
    Function<AdvisedRequest, String> requestToString,
    Function<ChatResponse, String> responseToString,
    int order
)

And Update the example to replace the incorrect userText reference with request.prompt().getUserMessage()