Add documentation of ModMimeUsePathInfo directive.

(When I did a rebuild, it wanted to regenerate every file, so I'm not
exactly sure what else is going to be checked in.  Did someone change
a master file without re-running the transformations?)


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@96724 13f79535-47bb-0310-9956-ffa450edef68