iio: backend: change docs padding

Using tabs and maintaining the start of the docs aligned is a pain and
may lead to lot's of unrelated changes when adding new members. Hence,
let#s change things now and just have a simple space after the member
name.

Signed-off-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20240426-ad9467-new-features-v2-1-6361fc3ba1cc@analog.com


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>