xdg-output: fix minor calculation error

Signed-off-by: Manuel Stoeckl <code@mstoeckl.com>
Reviewed-by: Simon Ser <contact@emersion.fr>

unstable/xdg-output/xdg-output-unstable-v1.xml

@@ -138,7 +138,7 @@
 	  advertise a logical size of 1920×1080,
 
 	- A compositor using a fractional scale of 1.5 will advertise a
-	  logical size to 2560×1620.
+	  logical size of 2560×1440.
 
 	For example, for a wl_output mode 1920×1080 and a 90 degree rotation,
 	the compositor will advertise a logical size of 1080x1920.