Merge r1179272, r1179266 from trunk:

* docs/manual: add note here in light of CVE-2011-3368

- add a security warning, and tweak the example, in light of CVE-2011-3368



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@1179283 13f79535-47bb-0310-9956-ffa450edef68