Docs: do not show argument types in function signature

[gipert]

No description provided.

[ManuelHu]

We will need more work to make this look nice.
At the moment we have a lot of parameters that are undocumented (i.e. they have no docstring). But their usage is still clear from the context if one knows the type. (i.e. the λ parameter, when one knows to pass a Quantity)

And with autodoc_typehints = "description", their type is not part of the docs at all. And I would also not really like if we would have to repeat a verbose docstring that the user has to pass a wavelength array multiple times...

[gipert]

Ok, I see your point. We can revert it to how it was before.