`exc_text` missing from LogRecord attributes table

# Documentation

The [LogRecord attributes table](https://docs.python.org/3/library/logging.html#logrecord-attributes) does not contain an entry for the `exc_text` attribute (which is [set when `Formatter.formatException` is called](https://docs.python.org/3/library/logging.html#logging.Formatter.format)).


### Linked PRs
* gh-140718