tests: spinlock: Add description and doxygen groups
tests: spinlock: Add description and doxygen groups

Add test description, RTM links and doxygen groups
for spinlock tests

Signed-off-by: Spoorthi K <c4ff46ff4cba9c2c6c6c9d55497ae534451b4309@intel.com>

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