doc: simplify WITH clause syntax in CREATE DATABASE

Reported-by: Rob <rirans@comcast.net>

Discussion: https://postgr.es/m/20211016171149.yaouvlw5kvux6dvk@localhost

Author: Rob <rirans@comcast.net>

Backpatch-through: 10

doc/src/sgml/ref/create_database.sgml

@@ -22,7 +22,7 @@ PostgreSQL documentation
  <refsynopsisdiv>
 <synopsis>
 CREATE DATABASE <replaceable class="parameter">name</replaceable>
-    [ [ WITH ] [ OWNER [=] <replaceable class="parameter">user_name</replaceable> ]
+    [ WITH ] [ OWNER [=] <replaceable class="parameter">user_name</replaceable> ]
            [ TEMPLATE [=] <replaceable class="parameter">template</replaceable> ]
            [ ENCODING [=] <replaceable class="parameter">encoding</replaceable> ]
            [ STRATEGY [=] <replaceable class="parameter">strategy</replaceable> ] ]
@@ -36,7 +36,7 @@ CREATE DATABASE <replaceable class="parameter">name</replaceable>
            [ ALLOW_CONNECTIONS [=] <replaceable class="parameter">allowconn</replaceable> ]
            [ CONNECTION LIMIT [=] <replaceable class="parameter">connlimit</replaceable> ]
            [ IS_TEMPLATE [=] <replaceable class="parameter">istemplate</replaceable> ]
-           [ OID [=] <replaceable class="parameter">oid</replaceable> ] ]
+           [ OID [=] <replaceable class="parameter">oid</replaceable> ]
 </synopsis>
  </refsynopsisdiv>