Document that most emoji won't display correctly on Windows

(cherry picked from commit 622f0b7d38)

doc/classes/Font.xml

@@ -5,8 +5,9 @@
 	</brief_description>
 	<description>
 		Font contains a Unicode-compatible character set, as well as the ability to draw it with variable width, ascent, descent and kerning. For creating fonts from TTF files (or other font formats), see the editor support for fonts.
-		[b]Note:[/b] If a DynamicFont doesn't contain a character used in a string, the character in question will be replaced with codepoint [code]0xfffd[/code] if it's available in the DynamicFont. If this replacement character isn't available in the DynamicFont, the character will be hidden without displaying any replacement character in the string.
-		[b]Note:[/b] If a BitmapFont doesn't contain a character used in a string, the character in question will be hidden without displaying any replacement character in the string.
+		[b]Note:[/b] If a [DynamicFont] doesn't contain a character used in a string, the character in question will be replaced with codepoint [code]0xfffd[/code] if it's available in the [DynamicFont]. If this replacement character isn't available in the DynamicFont, the character will be hidden without displaying any replacement character in the string.
+		[b]Note:[/b] If a [BitmapFont] doesn't contain a character used in a string, the character in question will be hidden without displaying any replacement character in the string.
+		[b]Note:[/b] Unicode characters after [code]0xffff[/code] (such as most emoji) are [i]not[/i] supported on Windows. They will display as unknown characters instead. This will be resolved in Godot 4.0.
 	</description>
 	<tutorials>
 	</tutorials>

doc/classes/Label.xml

@@ -6,6 +6,7 @@
 	<description>
 		Label displays plain text on the screen. It gives you control over the horizontal and vertical alignment and can wrap the text inside the node's bounding rectangle. It doesn't support bold, italics, or other formatting. For that, use [RichTextLabel] instead.
 		[b]Note:[/b] Contrarily to most other [Control]s, Label's [member Control.mouse_filter] defaults to [constant Control.MOUSE_FILTER_IGNORE] (i.e. it doesn't react to mouse input events). This implies that a label won't display any configured [member Control.hint_tooltip], unless you change its mouse filter.
+		[b]Note:[/b] Unicode characters after [code]0xffff[/code] (such as most emoji) are [i]not[/i] supported on Windows. They will display as unknown characters instead. This will be resolved in Godot 4.0.
 	</description>
 	<tutorials>
 		<link title="2D Dodge The Creeps Demo">https://godotengine.org/asset-library/asset/515</link>

doc/classes/RichTextLabel.xml

@@ -9,6 +9,7 @@
 		[b]Note:[/b] RichTextLabel doesn't support entangled BBCode tags. For example, instead of using [code][b]bold[i]bold italic[/b]italic[/i][/code], use [code][b]bold[i]bold italic[/i][/b][i]italic[/i][/code].
 		[b]Note:[/b] [code]push_*/pop[/code] functions won't affect BBCode.
 		[b]Note:[/b] Unlike [Label], RichTextLabel doesn't have a [i]property[/i] to horizontally align text to the center. Instead, enable [member bbcode_enabled] and surround the text in a [code][center][/code] tag as follows: [code][center]Example[/center][/code]. There is currently no built-in way to vertically align text either, but this can be emulated by relying on anchors/containers and the [member fit_content_height] property.
+		[b]Note:[/b] Unicode characters after [code]0xffff[/code] (such as most emoji) are [i]not[/i] supported on Windows. They will display as unknown characters instead. This will be resolved in Godot 4.0.
 	</description>
 	<tutorials>
 		<link title="BBCode in RichTextLabel">https://docs.godotengine.org/en/3.3/tutorials/gui/bbcode_in_richtextlabel.html</link>