[Keymap] Added preonic and mechmini 2 keymaps (#5202)

* added mechmini2 keymap

* added preonic keymap

* changed readme

* correction to mechmini 2 readme

* changes to preonic keymap

users/spacebarracecar/spacebarracecar.h

@@ -90,6 +90,8 @@ bool process_record_keymap(uint16_t keycode, keyrecord_t *record);
 
 #define CTLENT CTL_T(KC_ENT)
 
+#define EMOJI LWIN(KC_DOT)
+
 /*
 Templates for Keys, with custom shifted and non shifted Characters
 */