Clarify build requirements
Clarify build requirements

git-svn-id: https://svn.apache.org/repos/asf/jakarta/jmeter/branches/rel-2-2@555342 13f79535-47bb-0310-9956-ffa450edef68

Former-commit-id: 37552b9e61eadd6885d12a019b618904c9e219ee
ham1/jmeter,ham1/jmeter,benbenw/jmeter,apache/jmeter,etnetera/jmeter,apache/jmeter,etnetera/jmeter,benbenw/jmeter,etnetera/jmeter,ham1/jmeter,ham1/jmeter,apache/jmeter,etnetera/jmeter,apache/jmeter,apache/jmeter,etnetera/jmeter,ham1/jmeter,benbenw/jmeter,benbenw/jmeter