[Keyboard] Ymd09 config updates (#20124)

Co-authored-by: jack <0x6a73@protonmail.com>
Co-authored-by: Joel Challis <git@zvecr.com>
Co-authored-by: Drashna Jaelre <drashna@live.com>

keyboards/ymdk/ymd09/keymaps/default/keymap.c

@@ -1,3 +1,18 @@
+/*
+Copyright 2023
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 2 of the License, or
+(at your option) any later version.
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+
 #include QMK_KEYBOARD_H
 
 const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {