Minor update

[singer-yang]

Hello professor,

Thank you a lot for developing the awesome repo "odak", it has helped me a lot! Recently I found a minor bug in Rayleigh Sommerfeld function. My reference is Eq (9) in the paper "Modeling and propagation of near-field diffraction patterns: A more complete approach."

Best,
Xinge

[kaanaksit]

Thank you @singer-yang for bringing this one up. Please keep in mind that we mostly rely on odak.learn.wave these days but not odak.wave submodule. Thus, it is left a bit rusty and may be less polished. I will accept your changes. But I want to also ask from you to update THANKS.txt and CITATION.cff with your name in this pull request before I go ahead and accept your changes. Please also note that as I accept your commits, these updates won't be alive under pip until odak==0.2.7. Best practice here in these cases is to use the repository to install the latest and greatest in between versions. Thanks!