Minor documentation fix

Author: networkfusion

docs/01_menu_controls.md

@@ -7,7 +7,7 @@ Use the C-Up and C-Down buttons
 ### DD ROMs
 
 #### Expansion Disks
-To load an expansion disk (e.g. F-Zero X) browse to the N64 ROM and load it (but not start it) and then browse to the DD expansion file and press the `R` button.
+To load an expansion disk (e.g. F-Zero X) browse to the N64 ROM and load it (but not start it) and then browse to the DD expansion file and press the `L` or `Z` button.
 
 #### Disk swapping
 This feature is not currently available in the menu.