Simplify syntax diagram for REINDEX.

Since there currently is only one possible parenthesized option, namely
VERBOSE, it's a bit pointless to show it with "{ } [, ... ]".  The curly
braces are useless and therefore confusing, as seen in a recent question
from Karsten Hilbert.  Remove the extra decoration for the time being;
we can put it back when and if REINDEX grows some more options.

doc/src/sgml/ref/reindex.sgml

@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-REINDEX [ ( { VERBOSE } [, ...] ) ] { INDEX | TABLE | SCHEMA | DATABASE | SYSTEM } <replaceable class="PARAMETER">name</replaceable>
+REINDEX [ ( VERBOSE ) ] { INDEX | TABLE | SCHEMA | DATABASE | SYSTEM } <replaceable class="PARAMETER">name</replaceable>
 </synopsis>
  </refsynopsisdiv>