Confusing docs for pvlib.clearsky.ineichen and lookup_linke_turbidity

[williamhobbs]

When I read this line in pvlib.clearsky.ineichen docs

https://github.com/pvlib/pvlib-python/blob/6b9476b90892bd05726b237d9098f7536568a43a/pvlib/clearsky.py#L31

it made me think that default Linke turbidity values from SoDa are included in pvlib.clearsky.ineichen, but they are not. Perhaps it should read something like

Default values for monthly Linke turbidity available in :py:class:`~pvlib.clearsky.lookup_linke_turbidity` are provided by SoDa [4]_, [5]_.

Related, the docs for lookup_linke_turbidity don't include a description/reference for where the data came from (I assume it was SoDa, references 4 and 5 in ineichen...).

[cwhanse]

That docstring could use an example showing that getting to clearsky is a two-step procedure (lookup_linke_turbidity then ineichen) unless one brings their own turbidity data.