MFbed: Update the German documentation set.

doc/de_DE.ISO8859-1/books/handbook/desktop/chapter.sgml 1.69 -> 1.71
doc/de_DE.ISO8859-1/books/handbook/mail/chapter.sgml 1.135 -> 1.136
doc/de_DE.ISO8859-1/books/handbook/mirrors/chapter.sgml 1.423 -> 1.425
doc/de_DE.ISO8859-1/books/handbook/multimedia/chapter.sgml 1.119 -> 1.120
doc/de_DE.ISO8859-1/books/handbook/serialcomms/chapter.sgml 1.118 -> 1.119

Obtained from: The FreeBSD German Documentation Project.