Docs: fix \crosstabview example.

This example missed being updated when we redefined \crosstabview's
argument processing.

Daniel Vérité

doc/src/sgml/ref/psql-ref.sgml

@@ -4173,7 +4173,7 @@ numerical order and columns with an independant, ascending numerical order.
 testdb=&gt; <userinput>SELECT t1.first as "A", t2.first+100 AS "B", t1.first*(t2.first+100) as "AxB",</userinput>
 testdb(&gt; <userinput>row_number() over(order by t2.first) AS ord</userinput>
 testdb(&gt; <userinput>FROM my_table t1 CROSS JOIN my_table t2 ORDER BY 1 DESC</userinput>
-testdb(&gt; <userinput>\crosstabview A B:ord AxB</userinput>
+testdb(&gt; <userinput>\crosstabview "A" "B" "AxB" ord</userinput>
  A | 101 | 102 | 103 | 104 
 ---+-----+-----+-----+-----
  4 | 404 | 408 | 412 | 416