Fix broken link to rewritemap in rewritelock description

of the quickreference.
Relative anchors to directives may only be set, if we're
actually transforming the particular <modulesynopsis> document.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@96922 13f79535-47bb-0310-9956-ffa450edef68