Use double quotes rather than double quotes for libpq target anchors.

Per observation from Tom Lane that the previous patch to these files was
not consistent with what is done elsewhere in the docs.

doc/src/sgml/lobj.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/lobj.sgml,v 1.54 2010/08/09 12:00:24 rhaas Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/lobj.sgml,v 1.55 2010/08/10 02:56:46 rhaas Exp $ -->
 
  <chapter id="largeObjects">
   <title>Large Objects</title>
@@ -99,7 +99,7 @@
     <application>libpq</application> library.
    </para>
 
-   <sect2 id='lo-create'>
+   <sect2 id="lo-create">
     <title>Creating a Large Object</title>
 
     <para>