Changes as requested to UF2_BOARD_ID

from 
https://github.com/microsoft/uf2#files-exposed-by-bootloaders

The Board-ID field is machine-readable and consists of a number of dash-separated tokens. The first token is the CPU type, second is the board type, and third is the board revision. More tokens can be also added.

Author: markbirss

src/boards/raytac_mdbt50q_db_40/board.h

@@ -69,7 +69,7 @@
 //------------- UF2 -------------//
 #define UF2_PRODUCT_NAME        "Raytac MDBT50Q Demo Board 40"
 #define UF2_VOLUME_LABEL        "MDBT50QBOOT"
-#define UF2_BOARD_ID            "RAYTAC-MDBT50Q-DB-40"
+#define UF2_BOARD_ID            "nRF52840-MDBT50Q-1MV2"
 #define UF2_INDEX_URL           "https://www.raytac.com/product/ins.php?index_id=81"
 
 #endif // RAYTAC_MDBT50Q_DB_40_H