Document behavior of Preview tab with regard to default license

[pdurbin]

When a dataset has a non-default license, the Preview tab tells you it won't show you a preview until you accept terms:

This seems especially strange when in comes to image previewers because the image is shown on both the dataset page...

... and in search cards:

For now, I'm suggesting we at least document this (strange, to me anyway) behavior. Perhaps we can add a line near where we write "File previews are not available for restricted files unless they are being accessed using a Preview URL" at https://guides.dataverse.org/en/6.5/user/dataset-management.html#file-previews

For a real-world example, it would be nice to see the zip previewer/downloader at https://dataverse.lib.virginia.edu/file.xhtml?fileId=79676&version=1.2 where a non-default license is being used.