fix missing music mode legend (#6686)

keyboards/planck/keymaps/default/keymap.c

@@ -156,7 +156,7 @@ const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
  * ,-----------------------------------------------------------------------------------
  * |      | Reset|Debug | RGB  |RGBMOD| HUE+ | HUE- | SAT+ | SAT- |BRGTH+|BRGTH-|  Del |
  * |------+------+------+------+------+------+------+------+------+------+------+------|
- * |      |      |      |Aud on|Audoff|AGnorm|AGswap|Qwerty|Colemk|Dvorak|Plover|      |
+ * |      |      |MUSmod|Aud on|Audoff|AGnorm|AGswap|Qwerty|Colemk|Dvorak|Plover|      |
  * |------+------+------+------+------+------+------+------+------+------+------+------|
  * |      |Voice-|Voice+|Mus on|Musoff|MIDIon|MIDIof|      |      |      |      |      |
  * |------+------+------+------+------+------+------+------+------+------+------+------|