Add directive name, so that quickreference.xsl can extract default value correctly.

Add a summary and explain at which loglevel the module operates. (related to PR 59088)

r1827780, r1853624 in trunk

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1853625 13f79535-47bb-0310-9956-ffa450edef68