Consider publishing to AppImageHub

[errant253]

I just recently found out about the existence of AppImageHub, a central community repository for AppImages with 1603 apps on it as of writing. Since keyroost is already being provided as an AppImage anyway, it may be worth considering publishing there to potentially reach more users.

To be honest, I have never used AppImageHub or their AppImage Launcher and personally don't plan to, but this issue can be a good place to discuss the idea.

[framefilter]

I did the prep work to publish of AppImageHub based on the spec I was able to find. Will work on getting it published (assuming it is compliant with their policies) for the next release. Leaving open for now. Thanks for the suggestion @errant253.