• Fix role="directory" attributes (replace with class="directory") in <filename> elements, because there is no such attribute [1]
• Add further missing class="directory" attributes

[1] http://www.freebsd.org/cgi/cvsweb.cgi/doc/en_US.ISO8859-1/books/handbook/printing/chapter.sgml?rev=1.89

Reviewed by: trhodes, remko, keramida
Approved by: gabor (mentor)