I guess you have not configured any security on your jerkins instanceâ¦
As every build in a unsecured environment can be triggered by a URL like this: http://host:port/job/myjob/build?delay=0sec
there is no need for the option you'r searching for, but in a secure env tis option allows you to define some security token which you have to pass on with the URL above to trigger the build
so in short:
this option is only available/needed in a secure setup...
/Domi