Add documentation for themed icons (monochrome)

Author: syntaxerror247

tutorials/export/exporting_for_android.rst

@@ -100,6 +100,9 @@ There are two types of icons required by Godot:
 
 - **Main Icon:** The "classic" icon. This will be used on all Android versions up to Android 8 (Oreo), exclusive. Must be at least 192×192 px.
 - **Adaptive Icons:** Starting from Android 8 (inclusive), `Adaptive Icons <https://developer.android.com/guide/practices/ui_guidelines/icon_design_adaptive>`_ were introduced. Applications will need to include separate background and foreground icons to have a native look. The user's launcher application will control the icon's animation and masking. Must be at least 432×432 px.
+- **Themed Icons:** Starting from Android 13 (inclusive), Themed Icons were introduced. Applications will need to include a monochrome icon to enable this feature. The user's launcher application will control the icon's theme. Must be at least 432×432 px.
+
+.. caution:: It is mandatory to provide a monochrome icon. Failure to do so will result in the default Godot monochrome icon being used.
 
 .. seealso:: It's important to adhere to some rules when designing adaptive icons. `Google Design has provided a nice article <https://medium.com/google-design/designing-adaptive-icons-515af294c783>`_ that helps to understand those rules and some of the capabilities of adaptive icons.
 
@@ -110,6 +113,7 @@ If you don't provide some of the requested icons, Godot will replace them using
 - **Main Icon:** Provided main icon -> Project icon -> Default Godot main icon.
 - **Adaptive Icon Foreground:** Provided foreground icon -> Provided main icon -> Project icon -> Default Godot foreground icon.
 - **Adaptive Icon Background:** Provided background icon -> Default Godot background icon.
+- **Adaptive Icon Monochrome:** Provided monochrome icon -> Default Godot monochrome icon.
 
 It's highly recommended to provide all the requested icons with their specified resolutions.
 This way, your application will look great on all Android devices and versions.