Fix typo in v10 release notes

The new functions return a list of files in the corresponding directory,
not the name of the directory itself.

Pointed out by Gianni Ciolli.

doc/src/sgml/release-10.sgml

@@ -974,7 +974,7 @@
 -->
         <para>
          Add functions to return the log and <acronym>WAL</> directory
-         names (Dave Page)
+         contents (Dave Page)
         </para>
 
         <para>