Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=47656 Add information on system property replacement in config files.
Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=47656
Add information on system property replacement in config files.

git-svn-id: 79cef5a5a257cc9dbe40a45ac190115b4780e2d0@889615 13f79535-47bb-0310-9956-ffa450edef68

Nickname0806/Test_Q4,apache/tomcat,apache/tomcat,Nickname0806/Test_Q4,apache/tomcat,Nickname0806/Test_Q4,apache/tomcat,Nickname0806/Test_Q4,apache/tomcat