fix: restore revolt-desktop.desktop

Please make sure to check the following tasks before opening and submitting a PR

[x] I understand and have followed the contribution guide
[ ] I have tested my changes locally and they are working as intended (untested - I don't have an Arch install at hand)
[x] These changes do not have any notable side effects on other Revolt projects

This should resolve a comment by @wait-what on #123 - however, I'll also cc @xhayper in case they removed it for a specific reason