DOC: added missing para in vops

Author: Liudmila Mantrova

doc/src/sgml/vops.sgml

@@ -1307,6 +1307,7 @@ AND filter(betwixt(day, '2015-01-01', '2016-01-01'));
     </listitem>
 
     <listitem>
+     <para>
       The result of vector boolean operations is <literal>vops_bool</literal>.
       Since &project; requires predicate expressions to have a regular boolean type,
       you have to convert the result to the <literal>bool</literal> type using the
@@ -1318,6 +1319,7 @@ AND filter(betwixt(day, '2015-01-01', '2016-01-01'));
       Otherwise, <literal>true</literal> is returned, so vector operators will
       check the <literal>filter_mask</literal> value for the selected vector
       elements in subsequent operations.
+     </para>
     </listitem>
     <listitem>
     <para>