Is your feature request related to a problem? Please describe.

Some tools on Linux such as AppImageLauncher looks for the field X-AppImage-Version in the .desktop file for desktop integration and then adds them as a menu entry with the format appname (version) but if X-AppImage-Version is missing it will lead to appname (1) a hardcoded version of 1. Major Linux apps like KDE applications that offer an appimage do specify this field correctly.

Describe the solution you'd like

There must be a way for app developers to communicate their version information, the appimagetool for example supports the VERSION environment variable and automatically adds this field to the .desktop (View code)