[Keyboard] Add support for Drink Me (#8039)

* Add initial configuration and keymaps for Yatara Drink Me.

* Apply suggestions from code review

* Apply suggestions from code review

* Add transparent layers in VIA layout so there are four layers in total. Amend closing bracket indentation in keymap.c files.

keyboards/yatara/drink_me/keymaps/dormouse/keymap.c

@@ -0,0 +1,10 @@
+#include QMK_KEYBOARD_H
+
+const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
+    [0] = LAYOUT(
+        KC_SLEP,
+        KC_MUTE,
+        KC_VOLD,
+        KC_VOLU
+    )
+};

keyboards/yatara/drink_me/keymaps/dormouse/readme.md

@@ -0,0 +1,11 @@
+# Drink Me - Dormouse layout
+
+> The Dormouse slowly opened his eyes. ‘I wasn’t asleep,’ he said in a hoarse, feeble voice: ‘I heard every word you fellows were saying.’
+
+Sleep and volume control.
+
+![Drink Me - Default layout](https://i.imgur.com/VQXH512.png)
+
+```
+Sleep, Mute, Volume down, Volume up
+```

keyboards/yatara/drink_me/keymaps/dormouse/rules.mk

@@ -0,0 +1 @@
+EXTRAKEY_ENABLE = yes