Clarify documentation
Clarify documentation

git-svn-id: https://svn.apache.org/repos/asf/jmeter/trunk@1431457 13f79535-47bb-0310-9956-ffa450edef68

Former-commit-id: 511cb6f017712df1d712e3b38adcc1050922e6dd
benbenw/jmeter,apache/jmeter,apache/jmeter,benbenw/jmeter,ham1/jmeter,apache/jmeter,benbenw/jmeter,etnetera/jmeter,etnetera/jmeter,benbenw/jmeter,apache/jmeter,ham1/jmeter,etnetera/jmeter,apache/jmeter,etnetera/jmeter,ham1/jmeter,ham1/jmeter,etnetera/jmeter,ham1/jmeter