[perf_tests] user-login: Describe the individual steps of the performance scenario in README.md
[perf_tests] user-login: Describe the individual steps of the performance scenario in README.md

ldimaggi/fabric8-test,ldimaggi/fabric8-test,ldimaggi/fabric8-test,ldimaggi/fabric8-test,ldimaggi/fabric8-test,ldimaggi/fabric8-test