Update sct_compute_compression and sct_process_segmentation references

[valosekj]

This is a minor PR updating the sct_compute_compression and sct_process_segmentation references.

Namely, the PR:

• updates NeuroLibre preprint ref with peer-reviewed Imaging Neuroscience ref
• adds a ref to medrxiv preprint

Resolves: #4343

[joshuacwnewton]

The DOI links themselves all work for me! I just had some minor feedback on the formatting, since we now have a list of references.

I'm pre-approving since this is a very simple change. :)

[valosekj]

Thank you! I agree with your changes!

[mguaypaq]

The diff link checker worked! Although I'm not sure why it skipped 3 of the 5 URLs, they don't look like they match our excluded domains.

[joshuacwnewton]

The diff link checker worked! Although I'm not sure why it skipped 3 of the 5 URLs, they don't look like they match our excluded domains.

Ah!

• https://github.com/spinalcordtoolbox/spinalcordtoolbox/actions/runs/8618430295/job/23621894336#step:8:17
• 3bd391a