doc: Add comment to check_expected().
doc: Add comment to check_expected().

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