Fix output of tsquery example in docs.

The output for this query changed in commit 4e2477b7b8. Backport to 9.6
like that commit.

Patch by Justin Pryzby, per Yaroslav Schekin's report.

Discussion: https://www.postgresql.org/message-id/20201005191922.GE17626%40telsasoft.com

doc/src/sgml/textsearch.sgml

@@ -1623,9 +1623,9 @@ occurrences to display in the result.',
 
 <screen>
 SELECT to_tsquery('fat') &lt;-&gt; to_tsquery('cat | rat');
-             ?column?
------------------------------------
- 'fat' &lt;-&gt; 'cat' | 'fat' &lt;-&gt; 'rat'
+          ?column?
+----------------------------
+ 'fat' &lt;-&gt; ( 'cat' | 'rat' )
 </screen>
       </para>
      </listitem>