Update list_physical_devices and list_logical_devices Argument notes
Hi @kenfranko Can you please review this PR ? Thank you! Hi @SuryanarayanaY Can you please check @kenfranko's [comments](https://github.com/tensorflow/tensorflow/pull/60824#discussion_r1239106026) and keep us posted? Thank you! Done the suggested changes.
At present both the APIs `tf.config.list_physical_devices` and `tf.config.list_logical_devices` has an optional argument named `device_type` which takes a `string` as an argument. But When we pass a numeric value or strings other than expected('CPU' or 'GPU') both returns an empty list instead of raising the error.The behaviour is ok but this is not documented well.Hence I proposed a note for same.

Also the default value of the argument `device_type` is `None` but with default value both the APIs returns available physical/logical devices. This is not `intuitive` as for value `None` the APIs returning the respective devices. This may create some confusion among users. Hence I am adding the note of same to the documentation explicitly to avoid any confusion.

Attaching the [gist](https://colab.research.google.com/gist/SuryanarayanaY/68405fce0b68d53f094f875a4a7c5c42/57153.ipynb#scrollTo=C-CjbbaKu1Q6) as reference for the above results.

The issue discussed in #57153 .
