[PATCH] Fix a typo in svn-ref.xml

[wuzhouhui]

* en/book/ref-svn.xml
  Fix a typo
Index: trunk/en/book/ref-svn.xml
===================================================================
--- trunk/en/book/ref-svn.xml	(revision 5889)
+++ trunk/en/book/ref-svn.xml	(working copy)
@@ -756,7 +756,7 @@
         <term><option>--parents</option></term>
         <listitem>
           <para>Creates and adds nonexistent or nonversioned parent
-            subdirectories to the working copy or repository as part
+            directories to the working copy or repository as part
             of an operation.  This is useful for automatically
             creating multiple subdirectories where none currently
             exist.  If performed on a URL, all the directories will