Merge "testcase start service script fail on centos env"

diff --cc docs/testing/user/userguide/opnfv_yardstick_tc056.rst
Simple merge

diff --cc docs/testing/user/userguide/opnfv_yardstick_tc057.rst
Simple merge

diff --cc docs/testing/user/userguide/opnfv_yardstick_tc058.rst
Simple merge