Updated the documantation with newly added configuration features.
Added information where to find minimal shell config file.
Added information how to activate particular features.
Signed-off-by: Jakub Rzeszutko <jakub.rzeszutko@nordicsemi.no>
Move guides and APIs into separate directories and cleanup naming
introducing index files rather than named section files.
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
