nrf/readme: Update make flash command when defining board.
Update the "make flash" command sample to include BOARD parameter
when building for a specific target board.
@@ -54,7 +54,7 @@ By default, the PCA10040 (nrf52832) is used as compile target. To build and flas
Alternatively the target board could be defined:
make BOARD=pca10040
- make flash
+ make BOARD=pca10040 flash
## Compile and Flash with Bluetooth Stack
