NO-JIRA: [C++ broker book] Fixed table errors in Security.xml, causing PDF generation to fail.

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1609494 13f79535-47bb-0310-9956-ffa450edef68
NO-JIRA: [C++ broker book] HA chapter: minor cleanup.

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1609495 13f79535-47bb-0310-9956-ffa450edef68