App on Linux is missing an icon

[holmesworcester]

On linux I see a default icon instead of the app icon. We should use our standard icon on linux. Not sure how to achieve this!

[holmesworcester]

One user noted that they use https://github.com/TheAssassin/AppImageLauncher ... so we should confirm that our solution works with this.

[holmesworcester]

It looks like there's an upstream issue that makes this hard:

• issue in the tool we use: AppImage icon not working electron-userland/electron-builder#4617
• issue in the tool they use: How to set icon for AppImage binary itself ?? AppImage/AppImageKit#346

One solution would be offering more package options for linux, using electron-builder.

[holmesworcester]

A user reported that they could manually add the icon to the desktop file.