Changing DTD version to meet KDE 4.2

--- ./doc/en/index.docbook

+++ ./doc/en/index.docbook

@@ -1,5 +1,5 @@

 <?xml version="1.0" ?>

-<!DOCTYPE book PUBLIC "-//KDE//DTD DocBook XML V4.1.2-Based Variant V1.1//EN" "dtd/kdex.dtd" [

+<!DOCTYPE book PUBLIC "-//KDE//DTD DocBook XML V4.2-Based Variant V1.1//EN" "dtd/kdex.dtd" [

   <!ENTITY kcollectd "<application>kcollectd 0.8</application>">

   <!ENTITY kappname "&kcollectd;">

   <!ENTITY package "kcollectd">