Add atreus keyboard

keyboards/atreus/keymaps/custom/permissive_hold.h

@@ -0,0 +1,13 @@
+bool get_permissive_hold(uint16_t keycode, keyrecord_t *record) {
+    switch (keycode) {
+        case LT(1,KC_SPC):
+        case LT(2,KC_ENT):
+        case RALT_T(KC_ESC):
+        case LT(1,KC_TAB):
+            // Immediately select the hold action when another key is tapped.
+            return true;
+        default:
+            // Do not select the hold action when another key is tapped.
+            return false;
+    }
+}