Readme out of date - how to flash app

[epac-tom]

The readme is out of date - states we can use flash_ and a number of other targets that do not exist.

I'm going off what's generated in the makefile:

	@echo "The following are some of the valid targets for this Makefile:"
	@echo "... all (the default if no target is provided)"
	@echo "... clean"
	@echo "... depend"
	@echo "... edit_cache"
	@echo "... rebuild_cache"
	@echo "... BlinkyExample_bl"
	@echo "... BlinkyExample_bl_sd_app_merge"
	@echo "... BlinkyExample_bl_sd_app_merge_flash"
	@echo "... BlinkyExample_bl_sd_app_pkg"
	@echo "... BlinkyExample_pkg"
	@echo "... FLASH_ERASE"
	@echo "... FLASH_SOFTDEVICE"
	@echo "... START_JLINK_ALL"
	@echo "... START_JLINK_GDBSERVER"
	@echo "... START_JLINK_RTT"
	@echo "... uECC"
	@echo "... BlinkyExample"

But I don't see anyway to flash just the app, or app plus SD.

[epac-tom]

Worked it out, adding the following to the src level CMakeLists.txt
nRF5_addAppFlashTarget(${target} "${CMAKE_CURRENT_BINARY_DIR}/${target}.hex")
Easy when you know how :)