Clarify stdev/stdevp
Clarify stdev/stdevp

git-svn-id: https://svn.apache.org/repos/asf/jakarta/jmeter/trunk@1165143 13f79535-47bb-0310-9956-ffa450edef68

Former-commit-id: b6f1ff7bb946528012dcb341bd0505f48badf554
ham1/jmeter,apache/jmeter,benbenw/jmeter,apache/jmeter,ham1/jmeter,apache/jmeter,ham1/jmeter,ham1/jmeter,etnetera/jmeter,etnetera/jmeter,apache/jmeter,etnetera/jmeter,benbenw/jmeter,ham1/jmeter,benbenw/jmeter,apache/jmeter,etnetera/jmeter,etnetera/jmeter,benbenw/jmeter