Better way to make icons in GIMP

[KoBeWi]

Your Godot version: 3.5

Issue description: I stumbled upon this when reading some discussion https://docs.godotengine.org/en/stable/tutorials/export/changing_application_icon_for_windows.html#creating-an-ico-file The doc links a video tutorial to make icons in GIMP. But there is a much better way. There is a plugin for GIMP called "iconify" that does the same thing as in the video, but with a single click. I think it's worth to mention it in the docs.

The plugin registry, where I originally got the plugin, seems to be dead, but here's some archived page (I think?): https://github.com/pixlsus/registry.gimp.org_static/blob/master/registry.gimp.org/files/iconify2_1.scm Not sure how do you install this now.