Update .iso filenames in live-disk.md

[evlim]

No description provided.

[jacobgkau]

Not strictly necessary since we have a note that the filename changes periodically and may not be verbatim, but no problems with updating it.

[AlexanderK-S76]

If we're going to update this document, I think it makes far more sense to instead use a wildcard so that we don't have to update it every time going forward.

Downloads/pop-os_22.04_amd64_*.iso

or better yet, Downloads/pop-os_*.iso As this would work regardless of major update version for Pop!_OS or minor ISO version updates.

[AlexanderK-S76]

These commands would even omit the need for a both the standard and Nvidia versions being listed to my understanding, simplifying the document overall.

[jacobgkau]

Since checksumming unintended files shouldn't be dangerous, I wouldn't be opposed to switching to wildcards instead. I do think there's value in teaching people how to do it manually, but there's also value in making it easier to copy/paste to follow.