doc: move networking/bluetooth to user/developer guides
doc: move networking/bluetooth to user/developer guides

Include both networking and bluetooth in the user guides.

Signed-off-by: Anas Nashif <0d9952ec84ac43c159f6b7e7ed99a9080c00dd6e@intel.com>

galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,ldts/zephyr,galak/zephyr,GiulianoFranchetto/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,GiulianoFranchetto/zephyr,zephyrproject-rtos/zephyr,ldts/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,GiulianoFranchetto/zephyr,Vudentz/zephyr,ldts/zephyr,GiulianoFranchetto/zephyr,Vudentz/zephyr,Vudentz/zephyr,finikorg/zephyr,nashif/zephyr,explora26/zephyr,galak/zephyr,nashif/zephyr,explora26/zephyr,nashif/zephyr,finikorg/zephyr,Vudentz/zephyr,ldts/zephyr,zephyrproject-rtos/zephyr,explora26/zephyr,finikorg/zephyr,Vudentz/zephyr,finikorg/zephyr,explora26/zephyr,Vudentz/zephyr,ldts/zephyr,galak/zephyr,nashif/zephyr,explora26/zephyr,GiulianoFranchetto/zephyr