Fix output of tsquery example in docs.

The output for this query changed in commit 4e2477b. 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

Author: hlinnaka

doc/src/sgml/textsearch.sgml

@@ -1615,9 +1615,9 @@ 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>