Added my Balance 12 layout for Atreus (#3336)

* New Balance Twelve-based layout for the Atreus keyboard

* Rearrange cursor keys. Fix layout comment typo.

* Added Balance 12 layout for Atreus

* Changes following review.

keyboards/atreus/keymaps/yttyx/config.h

@@ -0,0 +1,12 @@
+#ifndef CONFIG_H
+#define CONFIG_H
+
+#define ONESHOT_TIMEOUT       500   // Time (in ms) before the one shot key is released
+
+// Disable some options to reduce firmware size
+#define NO_PRINT
+#define NO_ACTION_TAPPING
+#define NO_ACTION_MACRO
+#define NO_ACTION_FUNCTION
+
+#endif