docs: clarify trace function implementation used by default depending on Python version (#2067)

* docs: clarify trace function implementation used by default depending on the Python version

* Apply suggestions from code review

Co-authored-by: devdanzin <[email protected]>

* Apply suggestions from code review

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Co-authored-by: Ned Batchelder <[email protected]>
Co-authored-by: devdanzin <[email protected]>
1 file changed