As per the agreements in the Process Group Meeting, rework the procedure
to include external code so that it reflects the reality of Zehyr today
with the choice between modules and integration into the main tree, and
decouple the non-Apache v2.0 license side of the question from the
process from importing 3rd-party code.
Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>
