Add stephen-huan keymap and fix LED problem in the default Plaid keymap (#9306)

* change layers, add pinmode to fix LEDs

* fix LEDs by setting the pin mode

* edit README

* edit GPIO documentation, edit keymap

* add markov chain

* simplify LED logic

* undo documentation changes

* keymap changes, fix LED enum logic

keyboards/dm9records/plaid/keymaps/default/keymap.c

@@ -214,6 +214,10 @@ led_config_t led_config;
 
 //Set leds to saved state during powerup
 void keyboard_post_init_user(void) {
+  // set LED pin modes
+  setPinOutput(LED_RED);
+  setPinOutput(LED_GREEN);
+
   // Call the post init code.
   led_config.raw = eeconfig_read_user();