fix pos2usage->pod2usage typo

git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@1766 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689

appendixa/perl-desc.xml

@@ -59,7 +59,7 @@ files to Perl5-style library modules.</para></sect4>
 <para>pod2text converts pod data to formatted ASCII text.</para></sect4>
 
 <sect4><title>pod2usage</title>
-<para>pos2usage prints usage messages from embedded pod docs in 
+<para>pod2usage prints usage messages from embedded pod docs in 
 files.</para></sect4>
 
 <sect4><title>podchecker</title>