Move the application types descriptions from the CMake documentation
section to the application development one, to give them visibility
and also because they application development chapter is a better home
for them.
Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>
It is quite confusing to describe Zephyr's source tree layout in the
section for application development, given that applications do not need
to follow the exact same layout as the main tree.
Instead move this section to the contribution guidelines chapter.
Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>