docs: iio: add documentation for adis16480 driver

Add documentation for adis16480 driver which describes the driver
device files and shows how the user may use the ABI for various
scenarios (configuration, measurement, etc.).
Signed-off-by: Ramona Gradinariu <ramona.gradinariu@analog.com>
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20240528142409.239187-7-ramona.gradinariu@analog.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/iio/index.rst

@@ -19,5 +19,6 @@ Industrial I/O Kernel Drivers
 
    ad7944
    adis16475
+   adis16480
    bno055
    ep93xx_adc