doc: application: fix up "running an application"

Re-work this section for clarity, making it clearer where the division
between emulated and real hardware is, and cleaning up the
instructions. Also re-work for correctness, updating Kbuild-style
flash instructions to use CMake.

Also make sure users know they can flash and run from anywhere on the
system using cmake --build.

Signed-off-by: Marti Bolivar <marti@opensourcefoundries.com>
1 file changed