Overhaul the Bluetooth documentation to split it into manageable units
and include additional information, such as architecture and tooling.
Signed-off-by: Carles Cufi <carles.cufi@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>