Add the notion that negated values cannot stand alone as a requirement for...

Add the notion that negated values cannot stand alone as a requirement for access, and fixed some badly formatted examples.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1337810 13f79535-47bb-0310-9956-ffa450edef68