updated to MIT licensed board variant

variants/promicro_nrf52840/variant.cpp

@@ -0,0 +1,15 @@
+#include "variant.h"
+#include "wiring_constants.h"
+#include "wiring_digital.h"
+
+const uint32_t g_ADigitalPinMap[] = {
+  8, 6, 17, 20, 22, 24, 32, 11, 36, 38,
+  9, 10, 43, 45, 47, 2, 29, 31,
+  33, 34, 37,
+  13, 15
+};
+
+void initVariant()
+{
+}
+