Move Atreus50 to hardwired directory and update README

keyboards/handwired/atreus50/atreus50.c

@@ -0,0 +1,10 @@
+#include "atreus50.h"
+
+void matrix_init_kb(void) {
+
+    // Turn status LED on
+    //DDRE |= (1<<6);
+    PORTE |= (1<<6);
+
+	matrix_init_user();
+};