Update the EEPROMKeymap.setup() call to remove an obsolete argument

EEPROM-Keymap was recently changed to work differently, and thus the mode
argument became obsolete. This removes it from the call, and updates the comment
above it to match current reality.

Signed-off-by: Gergely Nagy <algernon@keyboard.io>

Author: algernon

Model01-Firmware.ino

@@ -525,8 +525,9 @@ void setup() {
   // To make the keymap editable without flashing new firmware, we store
   // additional layers in EEPROM. For now, we reserve space for five layers. If
   // one wants to use these layers, just set the default layer to one in EEPROM,
-  // by using the `settings.defaultLayer` Focus command.
-  EEPROMKeymap.setup(5, EEPROMKeymap.Mode::EXTEND);
+  // by using the `settings.defaultLayer` Focus command, or by using the
+  // `keymap.onlyCustom` command to use EEPROM layers only.
+  EEPROMKeymap.setup(5);
 }
 
 /** loop is the second of the standard Arduino sketch functions.