Documentation: iio: ad4000: Add new supported parts

Documentation: iio: ad4000: Add new supported parts

Commit <c3948d090080> ("iio: adc: ad4000: Add support for PulSAR devices"),
extended the ad4000 driver supports many single-channel PulSAR devices.

Update IIO ad4000 documentation with the extra list of supported devices.

Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
Link: https://patch.msgid.link/2b602abd0773af91e7ccd9dd7a2afe67f4792f95.1743110188.git.marcelo.schmitt@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>