Kconfig: Document new def_{int,hex,string} extensions
Kconfig: Document new def_{int,hex,string} extensions

These work like def_bool, setting the type and adding a default at the
same time. This extension fixes some Kconfig inconsistency.

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

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