Keymap: add yshrsmz keymaps (#3770)

* add ergo42 keymap

* add helix keymap

* add keymap for lets_split

* Add keymap for nyquist

* update keymaps to address review comments

- remove unneeded include
- use `#pragma once`

keyboards/lets_split/keymaps/yshrsmz/config.h

@@ -0,0 +1,35 @@
+/*
+This is the c configuration file for the keymap
+
+Copyright 2012 Jun Wako <wakojun@gmail.com>
+Copyright 2015 Jack Humbert
+
+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
+
+/* Use I2C or Serial, not both */
+
+#define USE_SERIAL
+// #define USE_I2C
+
+/* auto shift config */
+#define AUTO_SHIFT_TIMEOUT 150
+
+/* Select hand configuration */
+
+#define MASTER_LEFT
+// #define _MASTER_RIGHT
+// #define EE_HANDS