MFde: Update the German Documentation set.

doc/de_DE.ISO8859-1/books/developers-handbook/Makefile 1.23 -> 1.24
doc/de_DE.ISO8859-1/books/developers-handbook/book.sgml 1.55 -> 1.57
doc/de_DE.ISO8859-1/books/developers-handbook/chapters.ent 1.22 -> 1.23
doc/de_DE.ISO8859-1/books/developers-handbook/introduction/chapter.sgml 1.18 -> 1.20
doc/de_DE.ISO8859-1/books/developers-handbook/kernelbuild/chapter.sgml 1.3 -> 1.5
doc/de_DE.ISO8859-1/share/sgml/mailing-lists.ent 1.58 -> 1.67

Obtained from: The FreeBSD German Documentation Project