[Keyboard] added matrix 8xv2.0 additional (#9470)

* added matrix 8xv2.0 additional keyboard

* Apply suggestions from code review

Co-authored-by: James Young <18669334+noroadsleft@users.noreply.github.com>

* add copyright and speed up the matrix scanning

* Update keyboards/matrix/m20add/rules.mk

Co-authored-by: Drashna Jaelre <drashna@live.com>

Co-authored-by: James Young <18669334+noroadsleft@users.noreply.github.com>
Co-authored-by: Drashna Jaelre <drashna@live.com>

keyboards/matrix/m20add/rgb_ring.h

@@ -0,0 +1,23 @@
+/**
+ * @file rgb_ring.h
+ * @author astro
+ * @brief effects for the rgb ring
+ *
+ * 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/>.
+ */
+
+#pragma once
+
+void rgb_ring_init(void);
+void rgb_ring_task(void);