📝 Add recommended sizes for Windows ICO icons

For #6396
Please refer to https://msdn.microsoft.com/en-us/library/windows/desktop/dn742485(v=vs.85).aspx
[ci skip]

docs/api/native-image.md

@@ -35,6 +35,8 @@ quality it is recommended to include at least the following sizes in the icon:
 
 * 16x16
 * 32x32
+* 40x40
+* 48x48
 * 64x64
 * 256x256