[documentation-guide] Documented how to validate a document.

[jhradile]

commit aa9c6b3e04e727057818951125580bfc0a918ac6
Author: Jaromir Hradilek <jhradile at redhat.com>
Date:   Sat Mar 22 04:27:56 2014 +0100

    Documented how to validate a document.

 en-US/publican.xml |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)
---
diff --git a/en-US/publican.xml b/en-US/publican.xml
index 335d01f..1469b33 100644
--- a/en-US/publican.xml
+++ b/en-US/publican.xml
@@ -143,7 +143,13 @@
   </section>
   <section id="sect-publican-validating">
     <title>Validating a Document</title>
-    <remark>Hic sunt leones.</remark>
+    <para>
+      To check your document and ensure that all source files are valid DocBook XML, type the following at a shell prompt:
+    </para>
+    <synopsis><command>publican build --langs <replaceable>languages</replaceable> --formats test</command></synopsis>
+    <para>
+      Replace <replaceable>languages</replaceable> with a comma-separated list of language codes. Note that when you build a document as described in <xref linkend="sect-publican-building" />, Publican automatically validates it for you.
+    </para>
   </section>
   <section id="sect-publican-building">
     <title>Building a Document</title>