MFbed: Update the German documentation set.

books/handbook/Makefile fixes only
books/handbook/advanced-networking/chapter.sgml 1.379 -> 1.380
books/handbook/config/chapter.sgml 1.215 -> 1.216
books/handbook/disks/chapter.sgml 1.248 -> 1.251
books/handbook/l10n/chapter.sgml 1.115 -> 1.118
books/handbook/linuxemu/chapter.sgml 1.128 -> 1.129
books/handbook/mirrors/chapter.sgml 1.408 -> 1.411
books/handbook/ports/chapter.sgml 1.252 -> 1.253
books/handbook/ppp-and-slip/chapter.sgml 1.171 -> 1.172
books/handbook/security/chapter.sgml 1.288 -> 1.292

Obtained from: The FreeBSD German Documentation Project.