shell: kconfig: Put 'menuconfig SHELL' in top-level menu
shell: kconfig: Put 'menuconfig SHELL' in top-level menu

The 'Shell Options' menu contains just the 'menuconfig SHELL' menu in
the menuconfig interface.

Remove the 'Shell Options' menu and put 'menuconfig SHELL' directly in
the top-level menu instead. Also change the prompt from "Enable shell"
to just "Shell", to make it consistent with "Logging".

Signed-off-by: Ulf Magnusson <01743f1c1deb1fe75271d62edb65757d98ac0bcb@nordicsemi.no>

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