presence: fixed XML declaration allowed only at the start of the document

modules/presence/doc/presence_admin.xml

@@ -1,4 +1,4 @@
- <?xml version="1.0" encoding='ISO-8859-1'?>
+<?xml version="1.0" encoding='ISO-8859-1'?>
 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
 "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [