DOC: fixed typo in plantuner

Author: Liudmila Mantrova

doc/src/sgml/plantuner.sgml

@@ -18,7 +18,7 @@
     <para>
       This version of <filename>plantuner</filename> provides a
       possibility to hide the specified indexes from &productname;
-      planner, so it will not use them.For some workloads, &productname;
+      planner, so it will not use them. For some workloads, &productname;
       could be too pessimistic about newly created tables and assume
       that there are much more rows in a table than it actually has. If the
       <varname>plantuner.fix_empty_table</varname> GUC variable is set