Improve documentation around status.exception and status.message

### 👓 What did you see?

It is not clear from the documentation that `status.message` and `status.exception` add progressively more information.

### ✅ What did you expect to see?

Explanation from discord:

> If you don't have an exception use status.message
>
> If you do have an exception set status.message to the exception message. Also set status.exception.message to the exception message. And set status.exception.stacktrace to the message + stacktrace (if not included in the stacktrace by default).
>
> The rationale is a bit muddled but:
>
> Not every framework uses exceptions for control flow. So we have status.exception and status.message
>
> Some formatters separate exception.stacktrace and exception.message in their output. For example JUnit XML. So we have exception.message and exception.stacktrace.
>
> The end result is that each field gives progressively more information. None of fields exclude any of the others.

These relationships should be in the documentation.

### 📦 Which tool/library version are you using?

_No response_

### 🔬 How could we reproduce it?

_No response_

### 📚 Any additional context?

_No response_

Locate the documentation for status.message and status.exception; no file or test is named in the issue. Update that section to explain the progressively inclusive relationships described in the issue, then verify the rendered documentation makes the distinctions clear.

Written by the indexing model from the issue text.