[documentation-guide] added new section to XML chapter

[Laura]

commit 862752b840be99bf823c6e1beb8135803d885c87
Author: Laura Novich <lnovich at redhat.com>
Date:   Sun Mar 23 14:47:50 2014 +0100

    added new section to XML chapter

 en-US/tools.xml |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)
---
diff --git a/en-US/tools.xml b/en-US/tools.xml
index 2a3ae1b..6f9429b 100644
--- a/en-US/tools.xml
+++ b/en-US/tools.xml
@@ -51,7 +51,11 @@
 	<section>
 		<title>xmllint</title>
 		<para>
-		   some stuff to go here
+		   <package>xmllint</package> is a useful tool to use to check your XML files. Sometimes <command>publican build</command> will give you an error that may be difficult to interpret. <package>xmllint</package>'s parser can give more accurate details as to the location of the error and also can give you a description that makes more sense to a human. Another advantage to <package>xmllint</package> is that it can process a single XML file whereas <command>publican build</command> must parse the entire book. The <package>xmllint</package> package can be installed using the <command>yum install xmllint</command> as follows:
+		</para>
+		<screen># <command>yum install xmllint</command>.</screen>
+		<para>
+		   <command>xmllint <replaceable>name-of-file</replaceable></command>
 		</para>
 	</section>
 	<section>