Your Godot version: 4.0.2

Issue description:

There are various icon settings to set the game icon in different contexts for each platform:

• Project Settings > application/config/icon
• Project Settings > application/config/macos_native_icon
• Project Settings > application/config/windows_native_icon
• Export/Windows > application/icon
• Export/macOS > application/icon
  etc.

Currently, only Changing application icon for Windows explains about Project Settings > application/config/...icon changing the taskbar icon (apparently it's also reused as Window icon, but it's not written explicitly), and also tells us about macOS and other platforms as a side note, but there is no dedicated page like this for other platforms (probably because there is no complex process like rcedit for Windows).

Since there are just two fields to fill for other platforms (although technically Web > Progressive Web App and Android have more for different resolutions), it may not be worth a dedicated section for each like Windows, but then there could be a page that sums up all icon settings after the platform-specific Exporting... pages. Or you could have a sub-page in each platform-specific Exporting... section dedicated to icons.

The existing doc for Windows could also indicate that taskbar icon = window icon.

Filling tooltips would also be helpful so users don't even have to peek at the doc: each tooltip would explain what the field affects, and refers to other settings for completion.

For Project Settings > application/config/icon, I am personally unsure what it does, since Windows and macOS have more specific settings, Linux uses .desktop files, and mobile platforms don't have a taskbar/window system. But I'll try to give some tooltip example based on what I understood (I'm using property names in code for simplicity but they should be Title Cased in readable doc):

For instance:

• Project Settings > application/config/icon: sets ???. For Windows and macOS, set macos_native_icon and windows_native_icon for the taskbar/window icons, and in the Export window, application/icon for each platform for the application icon (not sure how they differ on macOS though)
• Project Settings > application/config/windows_native_icon: sets the taskbar/window icon on Windows. You must pass a native icon format .ico. For the application (desktop) icon for Windows, in the Export window, set application/icon.
• Export/Windows > application/icon: sets the application (desktop) icon for Windows. You can pass a simple image or native icon format .ico. For the taskbar/window icon on Windows, set Project Settings > application/config/windows_native_icon.

URL to the documentation page (if already existing): https://docs.godotengine.org/en/stable/tutorials/export/changing_application_icon_for_windows.html