Add generic F446Rx pinout (#877)

Author: MCUdude

boards.txt

@@ -1068,6 +1068,22 @@ GenF4.menu.pnum.FEATHER_F405.build.board=FEATHER_F405
 GenF4.menu.pnum.FEATHER_F405.build.product_line=STM32F405xx
 GenF4.menu.pnum.FEATHER_F405.build.variant=FEATHER_F405
 
+# Generic F446RE
+GenF4.menu.pnum.Generic_F446RE=Generic F446RE
+GenF4.menu.pnum.Generic_F446RE.upload.maximum_size=524288
+GenF4.menu.pnum.Generic_F446RE.upload.maximum_data_size=131072
+GenF4.menu.pnum.Generic_F446RE.build.board=GENERIC_F446RE
+GenF4.menu.pnum.Generic_F446RE.build.product_line=STM32F446xx
+GenF4.menu.pnum.Generic_F446RE.build.variant=Generic_F446Rx
+
+# Generic F446RC
+GenF4.menu.pnum.Generic_F446RC=Generic F446RC
+GenF4.menu.pnum.Generic_F446RC.upload.maximum_size=262144
+GenF4.menu.pnum.Generic_F446RC.upload.maximum_data_size=131072
+GenF4.menu.pnum.Generic_F446RC.build.board=GENERIC_F446RC
+GenF4.menu.pnum.Generic_F446RC.build.product_line=STM32F446xx
+GenF4.menu.pnum.Generic_F446RC.build.variant=Generic_F446Rx
+
 # Generic F411RE
 GenF4.menu.pnum.Generic_F411RE=Generic F411RE
 GenF4.menu.pnum.Generic_F411RE.upload.maximum_size=524288