Update buildAndProgram.md (#477)

Corrected typo in example usage of cmake BUILD_DFU option. Changed from -BUILD_DFU=1 to -DBUILD_DFU=1

Author: wilsonjwco

doc/buildAndProgram.md

@@ -27,7 +27,7 @@ CMake configures the project according to variables you specify the command line
 **NRFJPROG**|Path to the NRFJProg executable. Used only if `USE_JLINK` is 1.|`-DNRFJPROG=/opt/nrfjprog/nrfjprog`
 **GDB_CLIENT_BIN_PATH**|Path to arm-none-eabi-gdb executable. Used only if `USE_GDB_CLIENT` is 1.|`-DGDB_CLIENT_BIN_PATH=/home/jf/nrf52/gcc-arm-none-eabi-9-2019-q4-major/bin/arm-none-eabi-gdb`
 **GDB_CLIENT_TARGET_REMOTE**|Target remote connection string. Used only if `USE_GDB_CLIENT` is 1.|`-DGDB_CLIENT_TARGET_REMOTE=/dev/ttyACM0`
-**BUILD_DFU (\*\*)**|Build DFU files while building (needs [adafruit-nrfutil](https://github.com/adafruit/Adafruit_nRF52_nrfutil)).|`-BUILD_DFU=1`
+**BUILD_DFU (\*\*)**|Build DFU files while building (needs [adafruit-nrfutil](https://github.com/adafruit/Adafruit_nRF52_nrfutil)).|`-DBUILD_DFU=1`
 
 ####(**) Note about **CMAKE_BUILD_TYPE**:
 By default, this variable is set to *Release*. It compiles the code with size and speed optimizations. We use this value for all the binaries we publish when we [release](https://github.com/JF002/InfiniTime/releases) new versions of InfiniTime.