State how 'MOUSE_MODE_CAPTURED' actually works in the 'Input' docs

doc/classes/Input.xml

@@ -417,7 +417,8 @@
 			Makes the mouse cursor hidden if it is visible.
 		</constant>
 		<constant name="MOUSE_MODE_CAPTURED" value="2" enum="MouseMode">
-			Captures the mouse. The mouse will be hidden and unable to leave the game window, but it will still register movement and mouse button presses. On Windows and Linux, the mouse will use raw input mode, which means the reported movement will be unaffected by the OS' mouse acceleration settings.
+			Captures the mouse. The mouse will be hidden and its position locked at the center of the screen.
+			[b]Note:[/b] If you want to process the mouse's movement in this mode, you need to use [member InputEventMouseMotion.relative].
 		</constant>
 		<constant name="MOUSE_MODE_CONFINED" value="3" enum="MouseMode">
 			Makes the mouse cursor visible but confines it to the game window.