Discuss possible log-linear WCS handling in Spectrum1D

[rosteen]

Having Spectrum1D.__init__ handle log-linear scales itself would perhaps be a nice feature, but definitely a new feature/enhancement, and thus warrant a different issue (and probably some discussion if it's worth the effort).

Originally posted by @dhomeier in https://github.com/astropy/specutils/issues/832#issuecomment-877358133

This issue is mostly to have an active issue logging the fact that there was potentially more discussion to be had about this case after closing #832.