- Reference docbooks stylesheets using URL, instead of local file

doc/stylesheets/xhtml.xsl

@@ -2,7 +2,7 @@
 <xsl:stylesheet  
     xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
 
-<xsl:import href="/usr/share/xml/docbook/stylesheet/nwalsh/xhtml/docbook.xsl"/>
+<xsl:import href="http://docbook.sourceforge.net/release/xsl/current/xhtml/docbook.xsl"/>
 
 <!-- Stylesheets common for all transformations (xhtml, txt, fo) -->
 <xsl:import href="common.xsl"/>