Document Glow Upscale Mode project setting only affecting Forward+/Mobile

doc/classes/ProjectSettings.xml

@@ -2619,6 +2619,7 @@
 		</member>
 		<member name="rendering/environment/glow/upscale_mode" type="int" setter="" getter="" default="1">
 			Sets how the glow effect is upscaled before being copied onto the screen. Linear is faster, but looks blocky. Bicubic is slower but looks smooth.
+			[b]Note:[/b] [member rendering/environment/glow/upscale_mode] is only effective when using the Forward+ or Mobile rendering methods, as Compatibility uses a different glow implementation.
 		</member>
 		<member name="rendering/environment/glow/upscale_mode.mobile" type="int" setter="" getter="" default="0">
 			Lower-end override for [member rendering/environment/glow/upscale_mode] on mobile devices, due to performance concerns or driver support.

doc/classes/RenderingServer.xml

@@ -1259,6 +1259,7 @@
 			<param index="0" name="enable" type="bool" />
 			<description>
 				If [param enable] is [code]true[/code], enables bicubic upscaling for glow which improves quality at the cost of performance. Equivalent to [member ProjectSettings.rendering/environment/glow/upscale_mode].
+				[b]Note:[/b] This setting is only effective when using the Forward+ or Mobile rendering methods, as Compatibility uses a different glow implementation.
 			</description>
 		</method>
 		<method name="environment_set_adjustment">