add note about legacy graphics driver for display_lcd_rotate proper…

…ty (#1606)

* add note about legacy graphics driver

As noted in #1596 the `display_lcd_rotate` property is only valid for use with the legacy graphics driver, but it's not immediately obvious in the documentation, so I added a note to specify such

* update phrasing referencing `lcd_rotate` property

configuration/config-txt/video.md

@@ -663,7 +663,7 @@ If using the VC4 FKMS V3D driver (this is the default on the Raspberry Pi 4), th
 
 ### display_lcd_rotate
 
-Use `display_lcd_rotate` to rotate or flip the LCD orientation. Parameters are the same as `display_hdmi_rotate`.
+For the legacy graphics driver (default on models prior to the Pi4), use `display_lcd_rotate` to rotate or flip the LCD orientation. Parameters are the same as `display_hdmi_rotate`. See also `lcd_rotate`.
 
 ### display_rotate