[3.x] Clarify range of various ID values are 32 bit

doc/classes/OptionButton.xml

@@ -6,6 +6,7 @@
 	<description>
 		OptionButton is a type button that provides a selectable list of items when pressed. The item selected becomes the "current" item and is displayed as the button text.
 		See also [BaseButton] which contains common properties and methods associated with this node.
+		[b]Note:[/b] The ID values used for items are limited to 32 bits, not full 64 bits of [int]. This has a range of [code]-2^32[/code] to [code]2^32 - 1[/code], i.e. [code]-2147483648[/code] to [code]2147483647[/code].
 	</description>
 	<tutorials>
 	</tutorials>

doc/classes/PopupMenu.xml

@@ -6,6 +6,7 @@
 	<description>
 		[PopupMenu] is a [Control] that displays a list of options. They are popular in toolbars or context menus.
 		[b]Incremental search:[/b] Like [ItemList] and [Tree], [PopupMenu] supports searching within the list while the control is focused. Press a key that matches the first letter of an item's name to select the first item starting with the given letter. After that point, there are two ways to perform incremental search: 1) Press the same key again before the timeout duration to select the next item starting with the same letter. 2) Press letter keys that match the rest of the word before the timeout duration to match to select the item in question directly. Both of these actions will be reset to the beginning of the list if the timeout duration has passed since the last keystroke was registered. You can adjust the timeout duration by changing [member ProjectSettings.gui/timers/incremental_search_max_interval_msec].
+		[b]Note:[/b] The ID values used for items are limited to 32 bits, not full 64 bits of [int]. This has a range of [code]-2^32[/code] to [code]2^32 - 1[/code], i.e. [code]-2147483648[/code] to [code]2147483647[/code].
 	</description>
 	<tutorials>
 	</tutorials>

doc/classes/TreeItem.xml

@@ -6,6 +6,7 @@
 	<description>
 		Control for a single item inside a [Tree]. May have child [TreeItem]s and be styled as well as contain buttons.
 		You can remove a [TreeItem] by using [method Object.free].
+		[b]Note:[/b] The ID values used for buttons are limited to 32 bits, not full 64 bits of [int]. This has a range of [code]-2^32[/code] to [code]2^32 - 1[/code], i.e. [code]-2147483648[/code] to [code]2147483647[/code].
 	</description>
 	<tutorials>
 	</tutorials>