MFbed: Update the German website.

www/de/includes.sgml fixes only
www/de/includes.xsl fixes only
www/de/includes.navdownload.sgml fixes only
www/de/index.xsl 1.150 -> 1.151
www/de/docs/books.sgml 1.18 -> 1.21
www/de/docs/man.sgml 1.5 -> 1.7
www/de/news/news.xml 1.398 -> 1.404
www/de/news/press.xml 1.193 -> 1.196
www/de/releases/index.sgml 1.109 -> 1.110
www/de/security/security.sgml 1.184 -> 1.185

Obtained from: The FreeBSD German Documentation Project.