Modified help file to be clearer about how to use parameter in Ant script

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@12516 71c3de6d-444a-0410-be80-ed276b4c234a

war/resources/help/parameter/string.html

@@ -6,5 +6,5 @@
     <p>
     Note that when this field is exposed as an environment variable, it
     will be always in the upper case (e.g., the parameter "foo" would be exposed
-    as "FOO".)
+    as "FOO"). In Ant for example you access it by typing in ${env.FOO} 	
 </div>
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