Update docbook version

docs/Makefile

@@ -1,5 +1,5 @@
 all:
-	jade -i html -t sgml -V nochunks -d /usr/share/sgml/docbook/utils-0.6.9/docbook-utils.dsl\#html pisg-doc.sgml | w3m -dump -T text/html > pisg-tmp.txt
+	jade -i html -t sgml -V nochunks -d /usr/share/sgml/docbook/utils-0.6.10/docbook-utils.dsl\#html pisg-doc.sgml | w3m -dump -T text/html > pisg-tmp.txt
 	cat pisg-tmp.txt | ./modifytxt.pl > pisg-doc.txt
 	docbook2html pisg-doc.sgml -o html