doc: Add example for cmocka test case.
doc: Add example for cmocka test case.

aleksandr-vin/cmock,dsch/cmocka,nuumio/cmocka,jschmidlapp/cmocka,tyc/cmocka,clibs/cmocka,Odie/cmocka,jhrozek/cmocka,jschmidlapp/cmocka,VladimirTyrin/cmocka,tyc/cmocka,wingyplus/cmocka,jhrozek/cmocka,wingyplus/cmocka,jamesmunns/CMocka,jhrozek/cmocka,jamesmunns/CMocka,jschmidlapp/cmocka,JonathonReinhart/cmocka,nuumio/cmocka,lsjostro/cmocka,aleksandr-vin/cmock,Odie/cmocka,chadversary/cmocka,JonathonReinhart/cmocka,clibs/cmocka,chadversary/cmocka,dsch/cmocka,VladimirTyrin/cmocka,lsjostro/cmocka,nuumio/cmocka,linuxmaniac/cmocka,linuxmaniac/cmocka,tyc/cmocka,Odie/cmocka