DOC: grammar fixes in plantuner docs

Author: Liudmila Mantrova

doc/src/sgml/plantuner.sgml

@@ -1,50 +1,45 @@
 <sect1 id="plantuner">
   <title>plantuner</title>
   <para>
-    The <literal>plantuner</literal> module provides hits for planner,
-    which can disable or enable indexes for query execution.
+    The <filename>plantuner</filename> module provides hints
+    for the planner that can disable or enable indexes for query execution.
   </para>
 
   <sect2 id="plantuner-motivation">
     <title>Motivation</title>
     <para>
-      Whether somebody think it's bad or not, but sometime it's very
-      interesting to be able to control planner (provide hints, which tell
-      optimizer to ignore its algorithm in part), which is currently
-      impossible in &productname; (and PostgreSQL).
-      Oracle, for example, has over 120 hints,
-      and Microsoft SQL Server also supports hints.
+      In some cases, it may be required to control the planner
+      by providing hints that make the optimizer ignore some
+      parts of its algorithm. There are many situations when
+      a developer may want to temporarily disable specific
+      index(es), without dropping them, or to instruct the planner to
+      use a specific index.
     </para>
     <para>
-      This first version of plantuner provides a possibility to hide
-      specified indexes from &productname; planner, so it will not use them.
-    </para>
-    <para>
-      There are many situations when developer want to temporarily disable
-      specific index(es), without dropping them, or to instruct planner to
-      use specific index.
-    </para>
-    <para>
-      Next, for some workload &productname; could be too pessimistic for
-      newly created tables and assumes much more rows in table than
-      it actually has. If plantuner.fix_empty_table GUC variable is set
-      to true then module will set to zero the number of pages/tuples of
-      table which hasn't blocks in a file.
+      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;
+      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
+      to <literal>true</literal>, <filename>plantuner</filename> sets to zero
+      the number of pages/tuples of the table that has no blocks in a file.
     </para>
   </sect2>
 
-  <sect2 id="plantuner-syntax">
-    <title>Syntax</title>
-    <para>plantuner.disable_index &mdash; List of indexes invisible to planner</para>
-    <para>plantuner.enable_index &mdash; List of indexes visible to planner even they are hidden by plantuner.disable_index.</para>
+  <sect2 id="plantuner-guc-variables">
+    <title>GUC Variables</title>
+    <para><varname>plantuner.disable_index</varname> &mdash; list of indexes invisible to planner.</para>
+    <para><varname>plantuner.enable_index</varname> &mdash; list of indexes visible to planner even if they are hidden by <varname>plantuner.disable_index</varname>.</para>
   </sect2>
 
   <sect2 id="plantuner-usage-example">
     <title>Example</title>
     <para>
-      To enable the module you can either load shared library 'plantuner' in
-      psql session or specify 'shared_preload_libraries' option in
-      postgresql.conf.
+      To enable the module, you can either load <literal>plantuner</literal>
+      shared library in a <literal>psql</literal> session or specify
+      <varname>shared_preload_libraries</varname> option in
+      <filename>postgresql.conf</filename>.
       <programlisting>
 =# LOAD 'plantuner';
 =# create table test(id int);